(a) U.S. government securities will be sold by the fed in the open market.
The answer to b, c and d are the same and here it is;
Fed sells securities worth $200 million. Assuming Bank A purchases it, its required reserve will fall or drop by $50 million (0.25 required reserve). However, this will lead to a reserve shortage of $150 million. This will have to be made up by borrowing or selling assets or refusing to lend further the amount of loans that come due. Reduction in loan commitments reduces the second deposits of Bank B (reducing its reserve requirements but creating further reserve shortages) and the whole process proceeds just as in the case of expansion, until money supply is reduced by $800 million.
If We have a table of Banking System of assets and liabilities
Under Assets , we have that
Securities - $200m
Reserves - $200m
Loans - $800m
And under liability we will have
Demand deposit - $800m
e) If people decide to hold less cash in their pockets, it means that there's infusion of fresh funds into the banking system. This reduces the effect of multiple contraction. The reduction of money supply would be less than $800 million in the bank.