Unlike the female reproductive system, the male reproductive system
a. is affected by hormones.
b. utilizes a menstrual cycle, which is nearly 28 days long.
c. produces eggs.
d. is fully functional and able to produce and release active sperm after puberty

i am going to guess that it is co2.

tsd is temerature dependent sex determination.

tsd: it is a type of environmental sex determination in which the temperature experienced during embryonic/ larval development (ambient temperature for development) determine the sex of the offspring.

crocodile displays the tsd where the ambient temperature of the developing egg determines the individual's sex. for example in the american alligator's eggs, incubation at 33 ºc produces mostly males, while incubation at 30 ºc produces mostly females. so if the american alligator's egg will get the ambient temperature (33 degree celcius)during embryonic development from egg, the offspring will be male and same for the female sex determination.