What is the solution to this relative motion problem?

[temaire]

Homework Statement

http://img221.imageshack.us/img221/5571/kinematicslz1.jpg
I asked my teacher to clarify this question a bit more, and she said that the man wanted to end up exactly opposite to where he was on the west shore, or in other words, parallel to where he was from the east shore.

Homework Equations

soh cah toa
a^{2} + b^2 = c^2

The Attempt at a Solution

I think that the answer is B), because in order for him to end up exactly opposite of where he is, he must go west.
However, my teacher thinks that the answer is D). Who's right?

 

[temaire]

Can anyone help?

 

[awvvu]

If he goes straight west, he won't land directly opposite of his starting position, since the river will have pushed him north. Therefore he must travel at some angle south of west.

 

[temaire]

Sorry, I meant to say that the man wanted to go straight west, so he had to go 10kkm/h at an angle. But the question is asking for the actual velocity, or in other words, the ground velocity, which is, as I think, 8.0 km/h west.

 

[awvvu]

Yes, I suppose it depends on your interpretation of the question then.

 

[temaire]

Well it says actual motion.