Final answer:
A protein not very sensitive to pH changes may have many side chains with the amine group (-NH2), which act as buffers and help regulate acid-base balance.
Step-by-step explanation:
An important aspect of amino acids that affects the sensitivity of proteins to pH changes is the nature of their side chains, which are also known as R groups. A certain protein that is not very sensitive to pH changes may have many side chains with basic groups, particularly the amine group (-NH2). Basic amino acids such as lysine, arginine, and histidine have side chains with primary or secondary amine groups that ionize to cation -NH3+ or -NRH2+. These basic groups can absorb excess hydrogen ions or donate them, making them excellent buffers to help regulate acid-base balance. However, among the options given, the most relevant would be the -NH2 groups (option B), considering their ability to buffer changes in pH.