Question

Which of these are common to all mammals?

A: type of reproductive system, brain size, skin
B: digestive system, heart lungs
C: digestive system, number of toes, blood
D: kidneys, liver, skeletal structure

Answer 1

Answer is B

Step-by-step explanation:

All of the other ones are either for humans or other things not common to all species

Answer 2

The answer is D kidneys liver skeletal structure