Which type of attitude change is generally easier to bring about?

The correct answer is option 1: Congruent 

In general, positive attitudes are easier to change than negative attitudes are. Extreme attitudes, and central attitudes are more difficult to change than the less extreme, and peripheral (less significant) attitudes are. Simple attitudes are easier to change than multiple attitudes are.

It has been further found found that, in general, congruent changes are easier to bring about than are the incongruent changes in attitudes.