well it’s not a or b because that’s cutting 1/2 to an even smaller number;
1/2x4/5= 0.4, less than 1/2 or 0.5
1/2x1/2= 0.25 also less than 1/2 or 0.5
it’s not c either because 1/2x1/1 is just multiplying it by itself still being 1/2.
so d is the only answer because 1/2x5/4= 0.625 which is more than 0.5 or 1/2