abholaAh, but this is *not* a GMAT problem. In a real GMAT SC, the right answer will not contain any outright errors of grammar or meaning. This one does, in all 5 choices. We shouldn't try to learn from unofficial questions that make bad grammar look like an option.
If we're talking about a real GMAT question, then yes, if all 5 answers seem to be wrong, we need to step back and figure that something we *thought* was a problem must be okay after all. In that case, we start by eliminating the errors we're most sure about (e.g. subject-verb agreement), and then moving to the issues that may turn out to have more than one answer.