The esophagus has a simple but significant functions to animals who has it. These functions can be a) to swallow food and serve as a passageway to the stomach and b) may serve to release the eaten food that might have some harmful compositions or chemicals -the vomit response.
Answer:
Having a zygotic constitution of a specified kind:heterozygous.
The change in weather pattern caused forest to become sparse and hot weather caused the reduction of apes as they had less food and difficulty in surviving the climate.
Explanation:
In Miocene epoch volcanic mountain chains were created in Central Africa which abruptly changed the local weather.
The sea-level got drop due to global cooling of that time.
This resulted in continental drift making land connection of Africa with Eurasia.
The primates started migrating through this route.
The African forest become dry causing selective pressures in primates.
The cooler climate in Eurasia caused extinction and migration of primates to Africa in late Miocene epoch.
The hot and humid climate and less woodland caused a reduction in number of apes which were replaced by modern world monkeys.
The answer to your question is a