Which is a correctly written sentence, not a run-on?

a.
our cousins are coming for a visit we plan on taking them to the zoo and the museums.

b.
our backyard was all soggy from the rain, the dog's paws were all muddy.

c.
the gate to our backyard had been left open our dogs got out while we were gone.

d.
our car wouldn't start, so dad called a tow truck to take it to the mechanic.

The basketball crashed against the backboard, and point guard sheena lunged for it. as she snatched the ball out of mid-air, the crowd cheered, chanting encouragement for her team, the monarchs. so far, the game had been a disaster. with 15 seconds left to go in the final quarter, the monarchs were 2 points shy of victory. what main idea do the details in the passage suggest? the point guard sheena was not a very good player. the monarchs had never lost a basketball game. the monarchs were worried about losing. the crowd was not supporting the monarchs.