You are correct in your analysis. In a passage this sentence may be correct if "she" has a clear antecedent in the previous sentence. However, in simplistic terms, since in GMAT SC, the focus is on one sentence only, this will be considered incorrect.

Having said that, I should also state that typically GMAT sentences clearly state the name of "she" so that there is no ambiguity on this front. So the same sentence may be written as follows:

"Dreading another trip to the cat clinic, Maria persuaded her veterinarian to treat her cat at her home, ..."

And you may then question if all 3 occurrences of her have clear antecedent.

Hope that helps.

rsadana more or less summed it up. A lot of the GMAT does require common sense, but sometimes common sense will get you in trouble--in ordinary conversation, you'd certainly be able to figure out who "she" was, but in the isolated context of this SC problem, "she" could be Maria, or Daniella, or Samantha, or....

KapTeacherEli wrote:rsadana more or less summed it up. A lot of the GMAT does require common sense, but sometimes common sense will get you in trouble--in ordinary conversation, you'd certainly be able to figure out who "she" was, but in the isolated context of this SC problem, "she" could be Maria, or Daniella, or Samantha, or....

Thanks a lot KapTeacherEli and rsadana1