Choose the odd option among the following.

Correct option is A

The reasoning here is as follows:

In options 2, 3, and 4, the fractions 11/13, 1/3, and 2/3 are non-terminating decimals, meaning that their decimal expansions go on infinitely without repeating.
On the other hand, in option 1, 5/10 simplifies to 0.5, which is a terminating decimal, meaning it has a finite number of digits after the decimal point. This makes it different from the others.
Thus, option (a) is the odd one out.