What happened as a result of higher oxygen levels millions of years ago? (A)
Flowers started to be pollinated by bees.
(B)
Many insects had shorter lifespans than they have today.
(C)
Many insects grew to be bigger than they are today.
(D)
Flowers were unable to produce nectar.

A Flowers started to be pollinated by trees.

Explanation:

Hopefully this helps

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.