Which of the following is true about lactate dehydrogenase (LDH)?

A) There are two types of subunits, H amd M, that combine to form 5 types of isozymes
B) An increase in H-based isozymes was once used to diagnose heart attacks
C) An increase in blood levels of LDH of any kind is indicative of some sort of problem
D) One type of LDH has only H subunits
E) All of the choices