Statement:
“Mr. Mehta is accused of tampering with secret documents but if he denies the charges by swearing on Geeta, we shall withdraw the charges,” officers of a branch office tell the General Manager.
Assumptions:
I It is in the hands of the officers to withdraw charges.
II. Mr. Mehta is believed to be a very religious person.
III. The General Manager will agree to the proposal

The statement has two basic premises: a) Mr. Mehta is being accused of tampering with documents, and b) The officers are thinking about withdrawing the charges if Mr. Mehta swears on Geeta.

Now, we shall check each assumption by negation test (If the assumption is negated and, as a result, the statement stands invalid, it is a valid assumption). 

Assumption 1: Had it not been in the hands of the officers to withdraw the charges, they would not have spoken about the possibility of withdrawing the charges if Mr. Mehta had sworn on Geeta. Hence, this is a valid assumption. 

Assumption 2: On negating the assumption that 'Mr. Mehta is a religious person', so there is no effect on the main statement since even then, the sanctity of Geeta stands intact. Hence, this is not a valid assumption. 

Assumption 3: On negating the assumption that "General Manager will agree to the proposal', nothing would be done to the main statement as the officers have stated their plan of action, and there is no utility of pondering over the reaction of the General Manager.