What must happen for a solar eclipse to occur?

A solar eclipse occurs when the Moon comes between the Sun and the observer. This happens when the shadow cone of the Moon intersects the surface of the Earth, and is observable by anyone within this shadow zone. For an eclipse to occur the Moon must be near one of these intersection points (or nodes).

the answer for this question would be d. glaciers

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.