Answer:
a) Coastal regions, where climate is moderated by warmer ocean waves, have abundant flora and fauna.
Step-by-step explanation:
An adjective clause is a clause that functions as an adjective, describing the noun in the sentence. It contains a subject and a verb and stays next to the noun it modifies.
In the given pair of sentences, the second sentence can be turned into an adjective clause as it is talking about the subject "coastal regions" of the first sentence.
Thus, the rewritten sentence "Coastal regions, where climate is moderated by warmer ocean waves, have abundant flora and fauna" is the correct sentence using an adjective clause.