Which of the following explains the difference

Ex1: Cooks Ltd has a petty cash float with an imprest amount of £250. At the end of March, vouchers in the
petty cash box totalled £144 and the amount of cash remaining in the box was £86.
Which of the following explains the difference?
A/ A petty cash voucher for £20 is missing.
B/ An employee was given £20 too little when making a petty cash claim.
C/ An employee reimbursed petty cash with £20 in respect of postage stamps used, but no voucher
was prepared.
D/ A voucher for £20 was put in the box but no payment was made to the employee.
Ex2: Nozam maintains an imprest amount of £250 in petty cash. At the end of the month, he has vouchers
totalling £112, a receipt for a refund of £9 and a note to say that an employee took £10 to buy
stationery for which a voucher has not been prepared.
How much does Nozam need to withdraw from the business bank account to reinstate his imprest
balance at the end of the month?
A £113
B £93
C £137
D £127