What are the four tenets of natural selection?

1. More individuals are produced each generation that can survive.
2. Phenotypic variation exists among individuals and the variation is heritable.
3. Those individuals with heritable traits better suited to the environment will survive.
4. When reproductive isolation occurs new species will form.

I will have to agree with the person who already answered

They must use the scientific method

the glands which are associated with each description is given below:

pancreas - is an endocrine and exocrine gland that secretes juices with enzymes for digestion. salivary glands- with protection and digestion in the mouth. liver- secretes bile for digestion.   lachrymal glands - secrete tears to moisten eyes and protect them from particles and infection.   sweat gland -regulates water, salt, and temperature. oil glands - to form a protective barrier on the skin.   goblet cells - secrete mucus for protection.