In both the given sentences, the common word is weekly. In the first sentence, the word is an adjective, while in the second sentence it is an adverb. Thus, option C is correct.
Adjectives are the words that attribute to a name and modify the information given by the noun that describes it. Weekly is an adjective in the first sentence as it describes the events that occur once a week.
Adverbs are the words that are used in sentences that change the nouns, verbs, adjectives, clauses, etc. They show the time, frequency, degree, etc. In the second sentence, the word weekly expresses the time of the occurrence.
Therefore, option C. adjective and adverb are correct.
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