The right of people to gather for whatever nonthreatening purpose they desire is
a. peaceful assembly.
b. free speech.
c. freedom of religion.
d. freedom to protest.

The correct answer is: peaceful assembly. (Assembly means here "gathering" and peaceful: "nonthreatening" , so peaceful assembly has a similar meaning to "gather for whatever nonthreatening purpose").

the other options refer to other kinds of rights: free speech, freedom of religion and the freedom to protest. 

The right to peaceful assembly lets people gather for whatever nonthreatening purpose they desire. This law was established so that people could peaceably assemble and make a petition to the government to address anything that was considered wrong. The correct choice is letter

B. Peaceful assembly

I hope it helps, Regards.