Final answer:
The deadline for returning the life insurance policy to get a full premium refund is September 10th. Therefore, the none of option matches with the correct option.
Step-by-step explanation:
In this question, we are dealing with a business transaction related to insurance policy. The subject of this question is Business and the grade level is High School.
To determine the deadline for a full premium refund, we need to understand the timeframe given and how it relates to the policy delivery date. The policy was delivered on September 10th, and the options given are September 15th, September 20th, September 30th, and October 1st. To get a full premium refund, Don must return the policy no later than September 10th. Therefore, the correct answer is September 10th.