The flat fee is $4.00, which is added to the daily fee of $5.25. To find the cost of one week, we need to multiply the daily fee by the number of days, which is 7:
Daily fee = $5.25
Number of days = 7
Weekly fee = Daily fee x Number of days + Flat fee
= $5.25 x 7 + $4.00
= $36.75
Therefore, the cost of renting the saw for one week is $36.75.
So, the answer is B. $36.75.