Answer:
The word in the sentence that is an adverb is "badly".
Explanation:
An adverb is a part of speech that adds greater description to a verb, adjective, another adverb, a phrase, a clause, or another sentence. Most of them are easy to spot because they contain the suffix -ly. In the sentence above, the adverb "badly" is adding information as regards the frequency in which tomatos need water. It is an adverb of frequency.
