During human gestation, rudiments of all organs develop:
while the embryo is in the oviduct.
in the second trimester.
in the third trimester.
during the blastocyst stage.
in the first trimester.

First Trimester

Explanation:

While the normal human gestational period lasts for approximately nine months, the rudiments of all major organs arise during a relatively short period comprised (approximately) between the fourth and eight weeks of development.

Note that the embryo spends only the first 5-7 days in the oviduct, and begins implantation as a blastocyst with no organ rudiments per se.

it's c. (to reduce the greenhouse effect/carbon gasses)

not too sure but maybe in the hot springs.