Choose the best option for the given expression:- in the mean while

ad interim

The correct answer is Option (2) - ad interim

adieu - This means goodbye and wouldn't be appropriate in this context.

adios - Similar to adieu, it means goodbye in Spanish.
ad infinitum - This means "to infinity" and doesn't convey the idea of something happening during another thing.

"Ad interim" is a Latin phrase that translates to "in the meantime" and is the most fitting choice.