The inference questions in CR and RC portions are different from real world inferences.
Inference in GMAT means MUST BE TRUE, given the information at hand. So there should be no assumption, no new information required.
Most of the time, an easy inference question would be nothing more than a restatement of what is stated in the passage. If you cannot find a choice that is a restatement, go for a choice which would be reasonably true (ie you do not have to make unreasonable assumptions).
See if this tip helps you a little