Question

Which word in the sentence does the adverb clause modify? Although you cooked one cup of rice, it expanded to three. A. cooked B. rice C. three D. expanded

Answer 1

An adverb is how your doing something.  "He is talking 'gently'."

Clause is a side thing. Like a bill or contract.

so when the 1 grain of rice expanded you got 3.

I would go with C on this one. Hope I helped. :)