Which sentence needs revision to fix a grammar error? efinitely il cost al cost

Which sentence needs revision to fix a grammar error? efinitely
il cost
al cost
Sentence 1 should be revised to change "is" to "are."
Sentence 2 should be revised to change “will cost" to
"costs."
Sentence 3 should be revised to change "continue" to
"continued."
arth.
Sentence 4 should be revised to change “could help” to
"helps."