The correct answers are:
A. yo form
E. since Spanish is a phonetic language, the spelling change is necessary to maintain pronunciation when the preterit ending is added.
In the preterit, -car, -gar, and -zar verbs undergo spelling changes in the "yo" form to preserve their original pronunciation. For example, "buscar" changes to "busqué," "jugar" changes to "jugué," and "empezar" changes to "empecé."