Suppose we are solving a CSP with local search. The problem has N variables, each of which has a domain with d values (for example, in Sudoku, N = 81 and d = 9). We are interested in the successors of any state in the local search: from a given assignment to variables, what other assignments will we consider, from which we will choose the one with the minimal conflicts. Using O() notation, describe the computational complexity in terms of N and d for each of the following approaches to generating successors: 

a. Randomly choose a variable, then consider all assignments to that variable. 

b. For the variable with the most conflicts, consider all assignments to it.

c. Consider all states that differ by the assignment to exactly one variable. 

d. Consider all states that differ by the assignment to one or two variables. (This can be useful to escape from plateaus).