By including
in the speech the speaker is more likely to accomplish the goal of
a demonstrations, weakening attitudes, beliefs, or values
b. jokes, strengthening attitudes, beliefs, or values
c. pictures, motivating to action
d. data; changing attitudes, beliefs, or values

Option D.

Data; changing attitudes, beliefs, or values

Explanation:

When a speaker adds statistical data to prove the point, the audience's perception about things changes since the data implies that research has been conducted hence reliable. Consequently, the attitude of people and beliefs may change when such data is presented to them. Therefore, option D is correct.