At the lowest possible fuel flow the power levels would very low as such your airspeed would be low, so induced drag would become a factor as you would need a larger angle of attack, so you would travel less distance per litre of fuel burnt. (ie: maximum endurance)

thank you sir

The question asks for a speed to "cover the greatest possible [u]time[/u] per liter of fuel consumed". In other words, the question is asking for the [u]best endurance[/u] speed. It is a time question.

For any aircraft, best endurance occurs when the fuel flow is at a minimum for level flight. For a piston engine aircraft this will occur when the [u]power[/u] required for level flight is at a minimum. You may recall that FF is proportional to power in a piston engine aircraft - the lower the power setting, the lower the fuel flow, the greater the endurance.

With the above in mind, the correct answer is "C" not "B"

Thanks alot sir

In the current version of the CADA book, this is Question 4, with correct answer (c).