What was the relationship of Secretary of the Interior Albert Fall to the president?

The following statement is true about most congressional elections today:

a. Incumbents lose re-election most of the time. b. Incumbents don't get much attention from the media. c. Incumbency has no effect on the outcome of elections. d. The challenger does not need to raise a lot of money. e. Most congressional elections are not very competitive.

In a study using the gender of the participant as an independent variable, how many levels of the independent variable are there?

A) 1 B) 2 C) 3 D) None, since sex cannot be manipulated