Where is the BEST place to separate the run-on sentence into two sentences?

Sally likes taking her dog to the park they run on the paved trail.
A) after on
B) after dog
C) after run
D) after park

Aman lives on the twelfth floor of an apartment building. every morning he takes the elevator down to the lobby and leaves the building. in the evening, he gets into the elevator, and, if there is someone else in the elevator -- or if it was raining that day -- he goes back to his floor directly. otherwise, he goes to the tenth floor and walks up two flights of stairs to his apartment.