Sashin reads wikis at the beginning of his research project to get his bearings on the topic. He switches to peer$-$reviewed journals and professional publications for his formal sources. Why does Sashin not use wikis as formal sources?

Select one:

a$.$ No one is familiar with wikis.

b$.$ Wikis can be heavily biased.

c$.$ Users can post false information in wikis.

d$.$ Experienced editors verify changes made to wiki articles.