Optimization problem: A man launches his boat from Point A on a bank of a straight river...?

A man launches his boat from point A on a bank of a straight river, 2 km wide, and wants to reach point B, 2 km downstream on the opposite bank, as quickly as possible. He could row his boat directly across the river to point C and then run to B, or he could row directly to B, or he could row to some point D between B and C and then run to B. If he can row 6 km/h and run 8 km/h, where should he land to reach B as soon as possible?