It's most likely D. Here's why:
Answer A- The adverb 'quickly' is describing a verb, not adjective.
Answer B- The adverb 'loudly' is describing a verb, not adjective.
Answer C- The adverb 'sadly' is describing a verb, not adjective.
Answer D- 'Too' is an adverb that is being used to describe 'Cold', which is seen as an adjective in the sentence.