Chapter 4, Problem 1RA

Which of these statements about enzymes is true?

$\begin{array}{l}\text{a}\text{. Most proteins are enzymes}\text{.}\\ \text{b}\text{. Most enzymes are proteins}\text{.}\\ \text{c}\text{. Enzymes are changed by the reactions they catalyze}\text{.}\\ \text{d}\text{. The active sites of enzymes have little specificity for substrntes}\text{.}\end{array}$