If saving memory is a primary concern while implementing a divide$-$and$-$conquer approach we should prefer:

Iteration because of the use of stacks, the process is usually slower but needs less memory

Iteration as it consumes less. memory, but then it makes the code longer

Recursion because of the use of stacks, the recursion process is usually slower than iteration but needs less memory

Recursion as it consumes less memory, but then it makes the code longer