Methyl mercaptan (CH3SH) is a foul-smelling gas that is added to natural gas pipelines. Menthyl acetate (C12H22O2) contributes to the smell and flavor of peppermint. Methyl mercaptan has a molar mass of 48 g/mol.
Menthyl acetate has a molar mass of 198 g/mol.

If both substances were released at the same time, which one would you smell first? Why?

When you are making a guess you are forming a hypothesis

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.