Two rowers, who can row at the same speed in still water, head across a river.

the first rower (alice) heads straight across (but of course her boat is pulled downstream by the current).

the second rower (bianca) heads slightly upstream, so that with the pull of the current she arrives directly opposite their starting point.

who arrives at the other side first?

a) alice
b) bianca
c) it's impossible to tell without more information.