Female birds lay their eggs, thereby facilitating flight by ...

[federox]

Female birds lay their eggs, thereby facilitating flight by reducing weight. Which "strategy" seems most likely for female bats to use to achieve the same goal?
A) lay shelled eggs
B) limit litters to a single embryo
C) refrain from flying throughout pregnancy (about 6 weeks long)
D) give birth to underdeveloped young, and subsequently carry them in a pouch that has teats
E) feed multiple embryos internally using placentas

[theo]

Answer has to be B, 100%