At 7:00 p.m., the babysitter arrived at the apartment, no one was home.

What is the best way to rewrite this sentence?
a. At 7:00 p.m. the babysitter arrived at the apartment but no one was home.
b. At 7:00 p.m. the babysitter arrived at the apartment. But no one was home.
c. At 7:00 p.m., the babysitter arrived at the apartment: no one was home.
d. At 7:00 p.m., the babysitter arrived at the apartment; no one was home.