Based on the text, judge if the items below are right (C) or...

Resposta: certo.

Conforme explicita o texto, a Wikipedia está aberta à colaboração de todos. Eis alguns trechos:

Linha 4:  "(The free online encyclopedia)   ... is a symbol of unpaid collaboration..."

Linhas 8 e 9: "Every day thousands of people edit entries or add new ones..."

Consequentemente, está correta a assertiva do quesito, porquanto nem todos os artigos são enviados (submitted) por colaboradores individuais, eles também podem ser adicionados por associações coletivas, por empresas e por instituições.

Complementando: o trecho ...which advises organisations on how to create Wikipedia articles...mostra que não só colaboradores individuais alimentam a enciclopédia virtual.
Bom estudo!

c-
which advises organisations on how to create wikipedia articles (the very existence of such outfits hints at wikipedia's importance, as well as its susceptability to outside influence).

 

organisations != individual users.

 

The question's catch is in trying to lead the reader to peruse the text for information that is stated verbatim according to what is being suggested. Instead, it also behooves to search for any instance of what may not constitute "individual user".