Chapter 4, Problem 3RA

Which of these statements about lactate dehydrogenase is true?

$\begin{array}{l}\text{a}\text{. It is a protein}\text{.}\hfill \\ \text{b}\text{. It oxidizes lactic acid}\text{.}\hfill \\ \text{c}\text{. It reduces another molecule }\left(\text{pyruvic acid}\right)\text{.}\hfill \\ \text{d}\text{. All of these are true}\text{.}\hfill \end{array}$