Which is a unique feature of mars?
a.
the thick atmosphere—made mostly of carbon dioxide—absorbs solar radiation, heating up and make the atmosphere very hot
b.
it is the smallest planet and has the shortest period of revolution around the sun.
c.
the planet’s surface is covered with red, iron-oxide dust
d.
it is the only planet with permanent liquid water on its surface.

47

explanation:

ok

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.

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.