Earthworms and frogs breathe through their skin because of which the skin of both the organisms is

Answer is (b) It comes out with the CO2 during exhalation 

An organism which is simple is called primitive. On the other hand, an organism with high level of division of labour, by formation of organs and organ system is called...

(b) take in oxygen dissolved in water.

When we breathe out, moist air comes out (along with energy and carbon dioxide) which make the glasses wet (as water vapours get condense on glass).

(a) Skin,  Answer is correct

(b) Reproduction. 

Skin colour is controlled by three genes; A,B,C dominant genes and a,b,c the recessive genes ; the effect of each type of allele is addictive ; more the dominant allele,...

Fish- 2 chambered heart  frog - 3 chambered heart 

On counting, I breathe in and out for about 20 times in a minute.

(d) Most insects respire through tracheal system that lies on a network of small tubes that channel O2 directly to the different part of the body. The tracheal system is...