Which group of chordates does not possess true backbones?
a. crocodilians
b. lampreys
c. birds
d. frogs and toads

would it be a.?

No. Crocodilians are reptiles. and they are vertebrates, meaning they have a backbone. The answer is Lamprey.

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.