Question

The diagram below shows four coastline locations on Earth with respect to the moon at a given time.

Answer 1

The answer is both A and C. The coastlines that ideally experience high tides are places that are much nearer or opposite against the moon. The reason behind this is that the moon has its own gravitational field that pulls the earth towards itself. This makes high tides or low tides. Basically, there are two high tides and two low tides occuring at the same time. This is due to the varying forces that the moon does depending on the water's position on earth.

Answer 2

If you have the moon facing A and C on the picture then the answer is B and D.