Meaning: 'Makes' means to cause or enable something to happen, indicating that their small size allows them to move easily.

Wrong options:

• does: 'Does' is a helping verb that does not convey the action of enabling, making it grammatically incorrect in this context.
• gets: 'Gets' implies receiving or obtaining, which does not fit the context of describing the effect of size on movement.
• has: 'Has' indicates possession and does not convey the action of facilitating movement, making it unsuitable here.

Correct answer: source

Explanation: The word 'source' is appropriate as it refers to the origin of food, fitting grammatically and contextually as it describes the unusual food that marmosets consume.

Meaning: 'Source' means the place or thing from which something originates, in this case, the food that marmosets obtain.

Wrong options:

• diet: 'Diet' refers to the kinds of food a person or animal usually eats, but it does not specifically indicate the origin of that food, making it less precise here.
• habit: 'Habit' refers to a regular practice or routine, which does not fit the context of food acquisition.
• process: 'Process' implies a series of actions or steps taken to achieve a particular end, which does not accurately describe the food itself.

Correct answer: branches

Explanation: The noun 'branches' fits grammatically as it is a plural noun that refers to parts of a tree, which is contextually relevant as it describes where the holes are left after marmosets extract sap.

Meaning: 'Branches' are the parts of a tree that grow out from the trunk, which is where marmosets dig for sap.

Wrong options:

• skin: 'Skin' refers to the outer covering of an animal or human, which does not relate to the context of trees and is grammatically incorrect here.
• mouth: 'Mouth' refers to the opening in the face used for eating, which is irrelevant to the context of tree sap extraction.
• ground: 'Ground' refers to the surface of the earth, which does not fit the context of where the holes are made in relation to the trees.

Correct answer: danger

Explanation: The noun 'danger' fits grammatically as it indicates a state of being at risk, which is contextually appropriate as it describes the serious threat to marmosets and tamarins due to habitat loss.

Meaning: 'Danger' means the possibility of suffering harm or injury, indicating the risk of extinction for these animals.

Wrong options:

• doubt: 'Doubt' refers to uncertainty and does not convey a state of risk or threat, making it contextually inappropriate here.
• trouble: 'Trouble' implies difficulty but lacks the specific connotation of risk associated with extinction, making it less precise.
• way: 'Way' refers to a method or manner of doing something, which does not fit the context of describing a state of risk.