Meaning: 'Known' means recognized or familiar to people.

Wrong options:

• includes: 'Includes' is a verb that suggests the presence of additional elements, which does not fit the context of describing gunpowder as the only explosive.
• contains: 'Contains' implies the presence of components within gunpowder, which does not accurately describe its status as the only explosive.
• caused: 'Caused' is a verb that indicates a reason or effect, which does not fit the context of identifying gunpowder's status.
• unique: 'Unique' is an adjective that describes something as one of a kind, but it does not fit grammatically as it does not serve as a verb in this context.
• academic: 'Academic' is an adjective that relates to education or scholarly pursuits, which does not fit the context of describing gunpowder.

Correct answer: contains

Explanation: The word 'contains' is a verb that indicates the presence of potassium nitrate in gunpowder. It fits grammatically as it describes what gunpowder is made of, maintaining the logical flow of the sentence.

Meaning: 'Contains' means to have something within or as part of something else.

Wrong options:

• includes: 'Includes' suggests that there are additional elements beyond potassium nitrate, which is not the focus here.
• known: 'Known' is a past participle that does not fit as a verb in this context.
• caused: 'Caused' implies a reason or effect, which does not relate to the composition of gunpowder.
• academic: 'Academic' is an adjective that does not serve as a verb and does not fit the context of describing gunpowder's components.
• unique: 'Unique' is an adjective that does not fit grammatically as it does not describe the action of containing.

Correct answer: academic

Explanation: The term 'academic' is an adjective that describes the type of consensus regarding the invention of gunpowder. It fits grammatically and contextually as it indicates a scholarly agreement on the historical fact.

Meaning: 'Academic' refers to something related to education or scholarly work.

Wrong options:

• includes: 'Includes' does not fit as it does not describe the nature of the consensus.
• known: 'Known' does not fit grammatically as it does not describe the type of consensus.
• caused: 'Caused' is a verb that does not relate to the nature of consensus and does not fit in this context.
• unique: 'Unique' is an adjective that does not accurately describe the consensus as it does not convey the idea of scholarly agreement.
• led: 'Led' is a verb that does not fit as it does not describe the type of consensus.

Correct answer: led

Explanation: The word 'led' is the past tense of 'lead' and fits grammatically as it describes the result of the consensus regarding gunpowder's invention. It logically connects the invention to its subsequent uses.

Meaning: 'Led' means to guide or result in a particular outcome.

Wrong options:

• includes: 'Includes' does not fit as it does not describe the outcome of the invention.
• contains: 'Contains' is not appropriate here as it does not relate to the result of the invention.
• caused: 'Caused' implies a reason but does not fit the context of describing the outcome of the invention.
• academic: 'Academic' is an adjective that does not fit as it does not describe an action or result.
• unique: 'Unique' does not fit grammatically as it does not describe the action of leading.