The correct option is
D warm
In order to fill in the blanks with the most suitable adjective and adverb, let's understand what adjectives and adverbs are.Adjectives are the words that define/explain nouns or pronouns. For example: Roshni is pretty. Here, 'Roshni' is the noun and 'pretty' explains how she is, hence 'pretty' is the adjective.
Adverbs are the words that describe action words (verbs). For example: Ram fought bravely. Here, 'Ram' is the noun and 'fought is the verb. 'Bravely' describes how he fought, hence it is the adverb.
NOTE: We need a word to describe the type of clothes they were. Since, 'clothes' is a common noun, the word that describes it is called an adjective. Hence, we need an adjective to fill in the blank.
Option A - 'Warmth' is a noun and not an adjective. Thus option A is incorrect.
Option B - 'Warmly' is an adverb and not an adjective. Hence, option B is incorrect.
Option C - 'Warmful' is a wrong word. Thus option C is incorrect.
Option D - 'Warm' is an adjective which can be used to describe the type of clothes they wore. Hence, option D is the correct answer.
'We wore warm clothes in winter.'