An option is considered " at the money " when the current price of the underlying asset (or index level) equals the option’s strike price.

B is correct because the index level equals the strike price.

A is incorrect because " in the money " requires the option to have intrinsic value (e.g., for a call, the index level must be above the strike price).

C is incorrect because " out of the money " applies when the index level is below the strike price (for calls) or above it (for puts).

D is incorrect because " at the money " options have no intrinsic value.