The correct answer is C) Cumulus clouds lined up in rows extending in a northeast to southwest direction. To the west of an approaching tropical wave in the Northern Hemisphere, you would expect to see cumulus clouds forming in rows or lines oriented in a northeast to southwest direction. This is due to the counter-clockwise flow of air around the low-pressure system of the tropical wave, which causes convergence and uplift of moisture, leading to the formation of these cloud lines. The other options are incorrect because: A) Cirrostratus clouds would not be the expected cloud type; B) the cloud lines would not be oriented north-south; D) high altostratus clouds would not be the expected cloud type in this scenario.