A signaling molecule binding with a receptor molecule is like... A: the refrigerator in a house

B: a door in a house

C: the walls of a house

D: a key fitting into a lock

D

Explanation:

You are binding a key into a lock to make it open

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

the must be sensory neurons.  

hope its .

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.