Why this is the better choice??

GetridofG wrote:Although a surge in retail sales have raised hopes that there is a recovery finally underway, many economists say that wothout a large amount of spending the recovery might not last.
The correct answer should be "has raised hopes that a recovery is finally".
I don't understand why the answer above is the better choice. is that true in GMAT, it is better to avoid using THERE BE structure?

Without seeing the list of choices, here is what I think is correct
"say" is in the present tense
"have raised" is in the present perfect

The problem with the present perfect is that it does not agree with the subject
"surge in retail sales" is singular and require a singular present perfect, which is "has raised"

therefore the answer should have "has raised" present in the sentence.