The picture on the right shows the energy flow diagram of two trophic levels in leprosy forest. From this sentence, we can see that there are only two trophic levels in the picture, and the leprosy forest is the first known trophic level (plants are producers and will always be the first trophic level). Then A, B, C, D and E have only one trophic level, and there is "a-b-c" in the figure, so it is inferred that this is a detailed analysis of the energy destination of the second trophic level, including decomposition, respiratory consumption and biological development consumption. What can represent the second trophic level in the picture is B, C is the energy used by the second trophic level for growth and reproduction, and D is the energy consumed by respiration.

So we know that A is the energy eaten by the second trophic level, and the energy flowing from A to E is the energy of feces, which is eaten by the second trophic level but not digested and absorbed, that is, the energy that does not belong to the second trophic level. Answer: The energy transfer efficiency of Jatropha curcas to the next trophic level should be B/N.