To help you answer this question, you can search a sample reaction in the internet for hydroboration-oxidation. Take a look at the attached picture. The sample reaction is shown at the top. We can deduce that the original compound must be an alkene. Following the pattern, compound a must be 2-methylbutene as shown in the picture.
I think it is B the distance light travels from the sun to the earth
Electromagnets can be created by wrapping a wire around an iron nail and running current through the wire.