The correct options are
A Salvadora – Desert
C Abies – Coniferous forest
The ecological pyramids are an easy and efficient representation of the energy relationships, number of organisms and biomass of an ecosystem. Some of these limitations are as follows:
1.Some species belong to more than two or more trophic levels. This is particularly true in the case of consumers of higher trophic levels. Man is an example, he gets his food from primary producers as well as from higher trophic levels.Such organisms which feed at more than one trophic level are extremely difficult to depict in ecological pyramids.
2. Saprophytes play a vital role in each trophic level of the pyramid as they feed on dead and decaying parts of plant and animal matter but they are not represented in specific level in the ecological pyramids.