Ribozymes Were Discovered ________ Protein Enzymes,even Though They ________

Ribozymes were discovered ________ protein enzymes,even though they ________.

A) before; only catalyze one type of cellular reaction
B) before; are more heat labile than protein enzymes
C) after; catalyze many important cellular reactions
D) after; are the only catalysts found in bacteria and archaea
E) at the same time as; only catalyze one type of cellular reaction