In the desert food web shown below, which of the following best describes the transfer of energy between cacti and mule deer? about 90 percent of the cacti’s energy transfers to the mule deer. about 10 percent of the cacti’s energy transfers to the mule deer. about 10 percent of the mule deer’s energy transfers to the cacti. about 90 percent of the mule deer’s energy transfers to the cacti.

The correct option is B.
In the ecosystem, energy flows from one trophic level to the other. The first trophic level is that of the producers which use the energy of the sun to produce their own food. Out of the energy obtained from the sun by the producers only about 3% of it is converted into food products. The second trophic level is made up of the herbivores and the omnivores which eat the plant. Only about 10% of the energy from the plant is transferred to the animals in the second trophic level. These second trophic level animals will also transfer about 10% of the energy they obtain to the animals in the third trophic level when they are eaten. Thus, it can be seen that the energy that is transferred in the ecosystem is gradually reducing from one trophic level to another.