Answer:
The answer to your question is letter A. Regular size is cheaper than Economy size by $0.0003 per gram
Explanation:
Cost of 1 gr of economy size
5000 gr (5 kg) ------------------- $ 5.15
1 gr -------------------- X
x = 1 x 5.15 / 5000 = $0.0010
Cost of 1 gr of regular size
820 gr ------------------- $0.60
1 gr -------------------- x
x = 1 x 0.6 / 820 = $ 0.0007
Difference of cost = $0.0010 - $0.0007 = $0.0003