Which statement best explains why large predators, such as lions and leopards, are common in savanna grasslands, but are mostly absent from desert ecosystems?

a. there is not enough biomass at lower levels of the food chain in deserts for large predators to be supported.
b. biomass is passed through the food chain at a much higher rate of efficiency in grasslands, allowing large predators to exist.
c. there are no scavengers in deserts, but many in savannas, and this allows materials to cycle fast enough to support predators.
d. the 10% rule states that predators must make up 10% of the animals in ecosystems with a lot of biomass, like savanna ecosystems.