The correct options are
B Shifting cultivation made it difficult for the British to keep track of taxes.
C The British feared that the fire started by jhum cultivators would destroy the expensive timber.
The British banned shifting cultivation for two reasons. They wanted to utilise the timber from the forests, and the shifting cultivation would have destroyed the timber. Secondly, shifting cultivation made it hard for the British to collect taxes and track tax collection from jhum cultivators because they kept moving from one place to another.