imagne that you have decided to enter a short story competition organised by a teen magazine. The story must end with the following words " it's still a mystery to me at least 100 or 120 words

your awnser would be b.

comfortable

explanation:

one type of the adjectives is predicate adjective. a predicate adjective is an adjective which follows a linking verb and modifies or refers back to the main subject of that linking verb.

it usually is used just before the noun it modies.

here in this example:

'penguins seem comfortable in the coolest habitats', comfortable is the predicate adjective which follows the linking verb 'seem' and modifies the noun.

not sure maybe the subject closer to it or subject-verb agreement