Hi there,<br/><br/>There is a grammar question in my book. Here it is:<br/><br/>The article --- the famous author is still being criticized by the critics and columnists is full of controversial and radical ideas.<br/><br/>a- for which<br/>b- which<br/><br/>I don't understand this question. What is the difference between <del>for which</del> and <del>which</del>?