According to the passage, primary purpose of risk communication is to make lay people make an informed decision on matters involving the risk.
For this question, C, D, and E are just really really irrelevant.
C. Influencing the expert has never come up in the passage. Making lay people understand some technical information is all that author has talked about.
D. "Allay people's fear" is way too strong. This is NOT what risk communicators are for.
E. Focus is NOT on new technologies, but rather close to USING those new technologies SAFELY.
And between A and B,
For B, I actually thought that "promote" is more appropriate to describe what risk communicators are doing than "explain" to compare with A. This is why I chose B and got this wrong. But the next part of "justify" is clearly wrong. Justify means to prove or show to be right or reasonable. According to the passage, rick communicators never attempt to prove that they are right. This would be something scientists would do to show their theories are right. Risk communicators, according to line 3 of the first paragraph, falsely thought that they should "persuade" lay people. So, this is where B gets wrong.
For A, "rather than to persuade" is definitely corresponding the author's stand. In the first paragraph, the author states twice on being "persuasive" on informing lay people. Throughout the passage, also, the author highlights how it is important to letting lay people know, or EXPLAIN, correctly so that they can understand the true nature of risk. And this is why A is the Right Answer.