Why Might One Savanna Ecosystem Have 4 Trophic Levels, While

Why might one savanna ecosystem have 4 trophic levels, while a second one has 5?

A) The second ecosystem has less biomass of primary producers compared to the first.
B) The second ecosystem is a large savanna, while the first ecosystem is small.
C) The second ecosystem exhibits a greater loss of energy between trophic levels.
D) The second ecosystem has a higher rate of denitrification.