GMAT Critical Reasoning (CR) | Re: 2,500 individuals of voting age were polled and asked where

2,500 individuals of voting age were polled and asked where they stood on the political spectrum. 78% of these individuals described themselves as "moderate" in their political views; however, in the national elections that most closely preceded and followed the poll, over half of the individuals polled voted for candidates far to one end of the political spectrum. It follows that these individuals did not accurately describe their political views.

Which of the following is an assumption