What is the swap space in the disk used for?

Consider a program $$P$$ that consists of two source modules $${M_1}$$ and $${M_2}$$ contained in two different files. If $${M_1}$$ contains a reference to a function defined in $${M_2}$$, the reference will be resolved at.

Which of the following addressing modes are suitable for program relocation at run time?
$$1.$$ Absolute addressing
$$2.$$ Based addressing
$$3.$$ Relative addressing
$$4.$$ Indirect addressing

The minimum number of page frames that must be allocated to a running process in a virtual memory environment is determined by.