We are given:
a) That there are 6 pots, each a different size;
b) The total price of the 6 pots is $8.25;
c) Each pot costs $0.25 more than the next one below it in size

* Let the smallest pot be "X"
* Let the next biggest pot be "X + 0.25"
* Let the following pot be "X + 0.50". Following this logic, the largest pot is represented by "X + 1.25".

With the above, we can construct the following algebraic expression:

X + (X+0.25) + (X+0.50) + (X+0.75) + (X+1.00) + (X+1.25) = 8.25
6X + 3.75 = 8.25
6X = 4.50
X = 0.75

Therefore, the largest pot costs 0.75 + 1.25 = $2. Thus, the answer is C.