Problem Solving

At the post office, a letter must go through a sorting process with four distinct steps.
Step 1: Mail is picked up every half hour, beginning at 6:00 am.
Step 2: Mail is dropped off at the sorting center 1/4 hour later.
Step 3: Mail is sorted by zip code and stamped every hour, beginning at 7:00 am, and sent to regional sorting centers 1/3 hour later.
Step 4: At the regional sorting centers, incoming mail is put into the system every 30 minutes, beginning at 8:00 am, and sent to individual mail carriers 45 minutes later.

Assuming that all mail is picked up, sorted, and dropped off on time, what is the least total amount of time that it could take the letter to go through all four steps?

(A) 2 hours 45 minutes

(B) 2 hours 15 minutes

(C) 1 hour 45 minutes

(D) 1 hour 20 minutes

(E) 1 hour 15 minutes