Assertion (A) : An attitude may change in the direction of the information that is presented, or in a direction opposite to that of the information presented.
Reason (R) : Posters describing the importance of brushing one's teeth would strengthen a negative attitude towards dental care.

A is true, R is false

The correct answer is option 3: A is true, R is false

Assertion (A) : An attitude may change in the direction of the information that is presented, or in a direction opposite to that of the information presented. This is true. Attitude change can go in either direction — towards the presented information (when the message is persuasive), or against it.
Reason (R) : Posters describing the importance of brushing one's teeth would strengthen a negative attitude towards dental care. This is false. Posters promoting dental care (like brushing teeth) are intended to strengthen positive attitudes, not negative ones. Suggesting that they strengthen negative attitudes contradicts the purpose and general effect of such messages.