Why do you think solar panels would work well in space

They work well in space because they receive the full amount of sunlight without any atmosphere or clouds getting in the way. This assumes that objects such as other planets don't cover up the sun. Also, the spacecraft can't be too far away from the sun. If the spacecraft was at Pluto for instance, then the sun is not as effective as compared to at Mars.

where are the vectors ?

the answer is b, have negligible mass