Which of the Following Is True of the Effects of the Source

Which of the following is true of the effects of the source of a message on consumer attitudes?

A) The persuasive effect of source likeability is more on consumers with a high need for cognition than on those with a low degree of this trait.
B) The persuasive effect of source credibility tends to be highest when consumers lack the motivation to expend effort attending to the details of an ad.
C) The credibility of the source of a message does not have any impact on the certainty with which consumer attitudes are held.
D) Consumers with high involvement are not affected by the credibility of the source of a message.