Please answer all sections.

5. [8 points] A small business distributes 12 identical gift cards to its 21 employees. How many ways are there for it to distribute the gift cards if: (a) Each employee receives at most one gift card? (b) There are no restrictions on the number of gift cards a employee can receive? (c) There are no restrictions on the number of gift cards a employee can get, except that one particular employee, Steve, gets at least two gift cards? (d) There are no restrictions on the number of gift cards a employee can get, except that one particular employee, Steve, gets at most two gift cards