Why is the third line of defense consider specific and adaptive

The third line of defence against pathogenic invasion is the adaptive immune response, which has two key qualities: It is specific (it can differentiate between specific microorganisms and respond accordingly) It is adaptive (it can produce a heightened response upon re-exposure - in other words, it has memory)

Explanation:

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

the must be sensory neurons.  

hope its .

sulfur dioxide

explanation: acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. these substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.