The correct option is C.
Both DNA and RNA are made up of four nitrogenous bases. The nitrogenous bases that are found in DNA are adenine, guanine, cytosine and thymine. The nitrogenous bases that are found in RNA are adenine, guanine, cytosine and uracil.
Nicotine, once in the brain, will work specifically on nicotinic receptors in the brain. However, there is a common "addiction" pathway in the brain that pretty much all addictive substances go through.
A substance with pH 6 would be an acid, because it's 1pH to the left of a neutral substance
Nucleotides makes up each individual strand of DNA