First of all you need CAP 697,SEP 1 section page 6 (Table 2.2.3). That will give you a fuel flow of 68 lbs per hour (rounded up).
They have given you times for climb and descent, which is a hint that they should be added to the cruise time, the total makes 2.9 hours (rounded up).
2.9 x 68 = 197.2 + 6 (fuel correction for climb) makes 203.2 lbs for the trip fuel. The reserve is 30% of that, so divide by 1.3, take away the result from the trip fuel and add the remainder (46.89) to get 250.09. Add the start up and taxi fuel of 10 lbs to get 260, answer A. At least that's what I think it is
Isn't this in the wrong thread?