To answer this question, we need to understand who created YAMMER.
Option A) True - This option is correct because David Sacks did indeed create YAMMER. David Sacks is an American entrepreneur and investor who co-founded YAMMER in 2008.
Option B) False - This option is incorrect because David Sacks is the correct answer.
The correct answer is A) True. This option is correct because David Sacks created YAMMER.