The correct options are
B Shifting cultivation made it difficult for the British to keep track of taxes.
C Shifting cultivation destroyed the timber which the British wanted and had an added concern that the fire would destroy the forest.
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 settled in more than one place.