Why is this not an isomer of hexane?

BEZ IT THE structure of the HEXANE ITSELF

OTHERS R THE ISOMER OF THIS STRUCTURE.

AND THIS STRUCTURE DON'T CONTAIN A CARBON WITH LESS THAN 2 HYDROGEN ATOMS WHICH R COMPULSORY FOR A STRUCTURE TO BE A ISOMER

answer: the figure is attached herewith.

step-by-step explanation:   we are given to sketch a unit circle and label the terminal points corresponding to

in the attached figure, we have drawn a unit circle, with centre at o(0,0) and radius 1 unit. we have labelled the points a, b, c, d and e corresponding to the angles below

∠aox = 60°,

∠box = 120°,

∠cox = 180°,

∠dox = 240°,

∠eox = 300°.

and the coordinates are a(0.5,1), b(-0.5,1), c(-1,0), d(-0.5,-1) and e(0.5,-1).

thus, the answer is complete.

the answer is option a.