How can these sentences be combined to include a dependent clause?

The lifeguard was on duty. She pulled a toddler out of the pool.

AThe lifeguard was on duty; she pulled a toddler out of the pool.

BThe lifeguard was on duty, and she pulled a toddler out of the pool.

CWhile the lifeguard was on duty, she pulled a toddler out of the pool.

DWhen the lifeguard was on duty and pulled a toddler out of the pool.

What is the function of the noun clause in this sentence?
  whoever doesn't have a car will need a ride to the movie theater.

 A. indirect object
 B. appositive
 C. subject

 D. direct object