It measures the relative amount of hydrogen and hydroxyl ions in water. It’s important, because it’s an indicator that is changing chemicals of water.
The correct option is D. There are four different nitrogenous bases in DNA molecules; these bases are joined together by different forces including hydrogen bonds. In DNA molecules, there are two hydrogen bonds between adenine and thymine while there are three hydrogen bonds between cytosine and guanine. Thus, the hydrogen bonds between cytosine and guanine is the stronger.
