Question

Fill in the blank with a suitable adverb clause:
She earns more .

• A. than her husband
• B. money
• C. yet she isn't happy
• D. None of the above

Answer 1

The correct option is A than her husband

An adverb clause is a group of words containing a subject and a verb, and it functions as an adverb, by modifying an adjective, verb or an adverb. Adverb clauses generally begin with a subordinate conjunction (since, because, while, etc.).
Option A is correct because it is an adverb clause of comparison, "than" refers to comparison. (In comparison statements, the subordinate clause may not contain a subject and verb like in most clauses. The clause is elliptical; shortened such that the words are implied. In option A the verb is implied: than her husband does.)
Option B is incorrect because it is only a word, not a clause.
Option C is incorrect because it is a coordinate/independent clause, whereas an adverb clause is subordinate/dependent.
Option D is incorrect because the answer lies in A.