The mass number of an atom is the same as?
A. the protons it contains.
B. the neutrons it contains.
C. the number of protons and neutrons it contains.
D. the number of protons and electrons it contains.

Option C.

The number of protons and neurons it's contain.

Explanation:

Mass number of an atom is also called atomic mass of an atom which is some what expressed in Dalton i.e 1/2. The mass number is the total number of protons and neutrons altogether called nucleons in an atomic nucleus.

humans are now responsible for causing changes in the environment that hurt animals and plant species. we take up more space on earth for our homes and cities. we pollute habitats. human activity often changes or destroys the habitats that plants and animals need to survive.

where is the scientific experiment?