"Last but not the least, I would like to thank all the workers without whose co-operation," the rally wouldn't be a success.

Options

A. Last but not least, I would like to thank all the worker without their co-operation.
B. Last but not the least, I would like to thank all the workers without their co-operation.
C. Last but not least, I would like to thank all the workers without whose co-operation.
D. Last but not the least, I would like to thank all those workers without their co-operation.

Answer

C

Explanation

Corrects the idiomatic error. 'Last but not the least' is an idiom which means 'last but not less important than others'.