What characteristic is shared by birds, salamanders, and sharks?
a. lungs
b. endothermy
c. four limbs
d. jaws and paired appendages

(im pretty sure its not a or b but idk)

D. Jaws and paired appendages

Explanation:

Two pairs of appendages are present in sharks, birds and  salamanders. In the shark (fish) these appendages are fins, while in birds and  salamanders (land vertebrates) the appendages are limbs.  

Sharks, birds and  salamanders also have jaws. The jaw is an opposable articulated structure, typically used for grasping and manipulating food. Most vertebrates have jaws.

A) it is NOT ture because  sharks don't have lungs.

B. it is NOT true becasue salamanders are not endothermic.

C) it is NOT ture because  sharks are NOT four-limbed.

after receiving a stimus, the sensory receptors send(s) signals to the appropriate area of the body.  

the must be sensory neurons.  

hope its .