Meaning: Transferred means to move something from one place to another, in this case, oxygen moving to the bloodstream.

Wrong options:

• removed: 'Removed' is a past participle that implies taking something away, which does not fit the context of oxygen moving into the bloodstream.
• raised: 'Raised' is a verb that means to lift or elevate, which does not apply to the process of oxygen entering the bloodstream.
• stress: 'Stress' is a noun that refers to mental or emotional strain, which is unrelated to the action of oxygen transfer.
• extended: 'Extended' is a verb that means to stretch out or prolong, which does not fit the context of oxygen being taken into the bloodstream.
• formed: 'Formed' is a verb that means to create or shape, which does not apply to the transfer of oxygen.

Correct answer: removed

Explanation: The word 'removed' is a past participle that fits grammatically as it describes the action of carbon dioxide being taken out of the bloodstream. This is contextually appropriate as it follows the process of gas exchange in the lungs.

Meaning: Removed means to take something away or eliminate it, in this case, carbon dioxide being taken from the bloodstream.

Wrong options:

• transferred: 'Transferred' is a past participle that refers to moving something from one place to another, which does not fit the context of eliminating gas from the bloodstream.
• raised: 'Raised' is a verb that means to lift or elevate, which does not apply to the action of taking away carbon dioxide.
• stress: 'Stress' is a noun that refers to mental or emotional strain, which is unrelated to the removal of gas from the bloodstream.
• extended: 'Extended' is a verb that means to stretch out or prolong, which does not fit the context of gas removal.
• formed: 'Formed' is a verb that means to create or shape, which does not apply to the removal of carbon dioxide.

Correct answer: automatically

Explanation: The word 'automatically' is an adverb that fits grammatically as it describes how the lungs and respiratory system perform the gas exchange process without conscious effort. This aligns with the context of the body's natural functions.

Meaning: Automatically means occurring without conscious thought or effort, indicating that the process happens naturally.

Wrong options:

• transferred: 'Transferred' is a past participle that does not fit as it describes an action rather than how the lungs perform their function.
• removed: 'Removed' is a past participle that does not describe the manner in which the lungs operate, but rather an action related to gas exchange.
• stress: 'Stress' is a noun that refers to mental or emotional strain, which does not relate to the functioning of the lungs.
• extended: 'Extended' is a verb that means to stretch out or prolong, which does not fit the context of how the lungs perform their function.
• formed: 'Formed' is a verb that means to create or shape, which does not apply to the automatic functioning of the lungs.

Correct answer: stress

Explanation: The word 'stress' is a noun that fits grammatically as it refers to a condition that can negatively impact lung health. This is contextually relevant as it emphasizes the importance of reducing stress for maintaining healthy lungs.

Meaning: Stress refers to mental or emotional strain that can affect overall health, including lung function.

Wrong options:

• removed: 'Removed' is a past participle that implies taking something away, which does not fit in the context of what should be reduced for lung health.
• transferred: 'Transferred' is a past participle that refers to moving something from one place to another, which does not apply to the context of reducing negative factors for health.
• raised: 'Raised' is a verb that means to lift or elevate, which does not fit the context of reducing stress.
• extended: 'Extended' is a verb that means to stretch out or prolong, which does not relate to the concept of stress in this context.
• formed: 'Formed' is a verb that means to create or shape, which does not apply to the idea of reducing stress.