On 5 February 20XX, the quoted price of the June 20XX 90-day bank bill futures contract was 98.18, and the yield on 90-day bank accepted bills was 1.77 per cent per annum. On 12 February 20XX, the quoted price of the June 20XX 90-day bill futures contract was 98.19, and the yield on 90-day bank accepted bills was 1.78 per cent per annum. The basis on 12 February was:

a) -$613.91

b)$1350.40

c) -$1231.36

d) -$726.49

e) None of the above answers is correct.