Final answer:
A big idea is a creative concept that becomes central for communicating a message strategy and is designed to capture attention and persuade the audience.
Step-by-step explanation:
The correct answer is A) big idea. A big idea is a creative concept that becomes a point of focus for communicating the message strategy. It captures attention and should be vivid, personal, and concrete to be effective in persuasion, as also stated by Mckenzie-Mohr. In the context of social marketing, such as that practiced by Pride, a big idea could be the usage of a flagship species, which serves to evoke a positive emotional response and pride in the local environment, thereby motivating behavioral change.