Which of the following is position isomer of
:
Position isomerism:
Compounds having the same structure of the carbon chain but differing only in the position of the multiple (double or triple) bonds or the functional group are called positional isomers.
Now, option a and b cannot be the answer as the molecular formula is not the same.
But take a look at option C
There is a difference in the position of the double bond, the formula is the same.