Final answer:
The correct function name to fulfill the given requirements is def multiply_nth_element(lst, M, N).
Step-by-step explanation:
Out of the given options (a, b, c, d), the correct function name to fulfill the given requirements is def multiply_nth_element(lst, M, N).
The function takes three parameters: lst (the list), M (the multiplier), and N (the position at which to multiply the element).
To implement the function, you can iterate over the list using a for loop, checking if each index is divisible by N. If it is, you can multiply the element at that index by M.