An advertiser who works for a large company wants to make frequent, specific changes to bids based on criteria for more than 100,000 keywords. Which would be the most efficient tool for that advertiser to use?

An advertiser who works for a large company wants to make frequent, specific changes to bids based on criteria for more than 100,000 keywords. Which would be the most efficient tool for that advertiser to use? 

A) My Client Center (MCC)
B) AdWords Application Programming Interface (API)
C) AdWords editor 
D) Automatic cost-per-click (CPC) bidding