According to the phylogenetic tree, which two phyla are most closely related?

I believe the answer is echinodermata

echinodermata and Chordata have a very similar embryonic development; tirhe first opening (the blastopore) becomes the anus, while in protostomes it becomes the mouth and several similarties in the formation of skeleton.

It is predicted that Echinodermata and Chordata evolved from the same ancestor

answer; ///i believe its: ///(embolus);

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.