Question

find the error with subject-verb agreement. select the incorrect verb and type it correctly. at least fifty percent of residential water in the united states are used for landscaping purposes, and the majority of that is used to water lawns.

Explanation:

The subject "fifty percent of residential water" refers to a portion of an uncountable noun ("water"), so the verb should agree with a singular subject. The incorrect verb is "are"; it should be "is" to agree with the singular subject "water" (since the percentage refers to an uncountable quantity).

Answer:

Incorrect verb: are; Correct verb: is