In the text, the expression “peer reviewing” (l.22) refers to

Resposta: c

No texto, a expressão "peer reviewing" refere-se ao sistema usado pela Wikipedia para minimizar a publicação de informações falsas ( In the text, the expression "peer reviewing" refers to  the system used by Wikipedia to minimize the publication of false information).

O termo "peer reviewing" traduz-se por "revisão entre pares", ou seja, são os próprios colaboradores da Wikipédia que avaliam os artigos enviados pelos colegas. 

Essa assertiva está fundamentada na linha 22 do texto: "...Wikipedia's system of peer reviewing does a reasonable job of policing facts."

"Peer" está na mesma linha semântica de "accurate"
Segundo o MacMillan Dictionary, "peer" significa "to look very carefuly, especially because something is difficult to see".

c-

Peer review is work done on a collaborative basis where someone does the main research/paper which in urn is reviewed by a commission, usually made up of people of similar standing to the original researcher, unlike a paper written by a student and corrected by a faculty member.