Final answer:
Jill's gross weekly salary, considering her commission, if she sold $9000 worth of products, is $752(option c).
Step-by-step explanation:
Jill's gross weekly salary, considering her commission, if she sold $9000 worth of products, is: $752.
In the given information, we can see that for every $3000 worth of products Jill sells, she earns a commission of $900. Therefore, for $9000 worth of products, she would earn a commission of $2700.
Adding her base salary, which is not stated in the question, we can calculate her gross weekly salary as $2700 + base salary. The answer choice closest to this amount is $752. Therefore, the correct answer is C. $752.