How does value-based bidding work?

a. Value-based bidding is a Smart Bidding strategy that uses machine learning to drive the highest clickthrough rate possible, by bidding for conversions that drive business objectives.
b. Value-based bidding is a Smart Bidding strategy that uses machine learning to drive the highest impressions possible, by bidding for conversions that drive business objectives.
c. Value-based bidding is a Smart Bidding strategy that uses machine learning to drive the highest target impression share possible, by bidding for conversions that drive business objectives.
d. Value-based bidding is a Smart Bidding strategy that uses machine learning to drive the highest conversion value possible, by bidding for conversions that drive business objectives.