Pack 3 Q1 Electricity at first began coming

Electricity at first began coming into houses through direct current because of safety issues created by the high voltage of alternating current, but transformers safely lowered the voltage for use indoors, removing the only advantage direct current had compared to the efficiency of alternating current over long distances.

Ⓐ Electricity at first began coming into houses through direct current because of safety issues created by the high voltage of alternating current, but
Ⓑ Electricity coming into houses through direct current because the high voltage of alternating current created safety issues, but
Ⓒ Because electricity came into houses through direct current, since the high voltage of alternating current created safety issues,
Ⓓ At first, electricity came into houses through direct current because the high voltage of alternating current created safety issues, but
Ⓔ While electricity came into houses through direct current, the high voltage of alternating current creating safety issues, but

in options C and E there is starts with because and while , making missing main clause issues in themi.e,
c) Because electricity came into houses through direct current,
e)While electricity came into houses through direct current, the high voltage of alternating current creating safety issues, but

where as in options A and B there is verb tense issue , instead of continuous tense i.e, coming in these sentences , "came" serves better.