The ease with which attitudes can be changed depends on a number of factors, including:
a. message source.
b. characteristics of the message.
c. characteristics of the target.
d. all of these.

The best answer to the question: The ease with which attitudes can be changed depends on a number of factors, including:___, D: All of these.

Explanation:

An attitude is defined as a response a person has, or a behavior a person assumes, towards a situation, an event, or a person or object. Because attitudes are so individualized, they depend on a series of factors that are tightly tied to the individual, his personality, his genetics and his upbringing. In this case, in order to change a person´s attitude, then, the following factors need to be kept in mind: the message source, meaning where the message comes from, the characteristics of the message, because it will affect how the person perceives the message, and the characteristics of the target, because these will play a definitive role on how the message is interpreted. This is why the answer is D.