Lysozyme Is an Enzyme That Is Able to Break Down

Lysozyme is an enzyme that is able to break down the cell walls of bacteria. Langur monkeys and ruminants (such as cows) are the only known mammals in which lysozyme functions in the stomach instead of in tears and saliva. The cow/langur enzyme also has five amino acid changes that are not present in other mammals. What is most likely to be true about lysozyme from langurs and cows compared to lysozyme from other mammals?

A) The five amino acids that langurs and cows have in common in their lysozyme were present in the common ancestor of all mammals.
B) These five amino acid changes somehow make the cow/langur lysozyme resistant to pepsin digestion.
C) Salivary and tear lysozyme functions best at a higher H⁺ ion concentration than the cow/langur enzyme.
D) These five amino acid changes alter the specificity of the enzyme, such that the cow/langur lysozyme attacks viruses instead of bacteria.