The correct option is
C heavy, heavily
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: The first blank requires an adjective to describe the bag, and the second blank requires an adverb to describe how it was raining.
Option A - 'Heavy' is an adjective and hence can't be used to fill in both the blanks. Thus option A is incorrect.
Option B - 'Heavily' is an adverb and hence can't be used to fill in both the blanks. Hence, option B is incorrect.
Option D - 'Heavily' is an adverb and 'heavy' is an adjective. As we need an adjective for the first blank and an adverb for the second blank, we can't use 'heavily, heavy' here. Thus option D is incorrect.
Option C - 'Heavy' is an adjective which can be used to describe the bag. 'Heavily' is an adverb which can be used to describe the way it was raining. Hence, option C is the correct answer.
'My bag was very heavy and it was raining very heavily.'