Mark the sentence in which the idea introduced by the word ...

"as well as curtail the common practice of cc-ing everybody when sending out an e-mail." (lines 11-13) – contrast

"but when an e-mail goes out and five people get cc-ed," (lines 15-16) – reason.

"In fact, he loves it." (lines 18-19) – condition.

"Besides, during tough economic times, who will want to miss any information…" (lines 30-32) – addition

"Work is very seductive, but yet we're actually less effective." (lines 52-53) – consequence