A fuel with octane number 90 means it is as good as a mixture of :
(a) 90% Isooctane + 10% n-heptane
(b) 90% n-Heptane + 10% isooctane
(c) 2 Litre of 90% isooctane + 2 litre of benzene
(d) 2 Litre of 90% n-heptane + 2 litre of benzene
(a) 90% Isooctane + 10% n-heptane
(b) 90% n-Heptane + 10% isooctane
(c) 2 Litre of 90% isooctane + 2 litre of benzene
(d) 2 Litre of 90% n-heptane + 2 litre of benzene