The correct answer is: B. Backtrack search.
Backtracking is a recursive algorithm for finding all solutions to a problem. It works by trying all possible combinations of values for the variables in the problem, and backtracking when it finds a solution that is not valid.
In the context of the question, backtracking search is used to find all possible solutions to a problem where each variable can have only one of a finite number of values. The search starts by assigning a value to the first variable, and then backtracks if that value is not valid. It then assigns a value to the second variable, and backtracks if that value is not valid, and so on. The search continues until all possible values for all variables have been tried, or until a solution is found.
The other options are incorrect for the following reasons:
- A. Forward search is a type of search that starts at the root node of a search tree and expands nodes in a depth-first order. It is not a backtracking search.
- C. Hill algorithm is an algorithm for finding the minimum of a function over a given domain. It is not a backtracking search.
- D. Reverse-Down-Hill search is an algorithm for finding the maximum of a function over a given domain. It is not a backtracking search.