Which of the following statements is true?

DPLL can be used for reasoning

DPLL returns a model if a set of clauses is satisfiable

In the worst case, DPLL has to try out all $2^n$ possible assignments (if there are $n$ variables).

DPLL cannot find satisfying assignments for clause sets that are tautologies.

Given the following set of clauses:
$\Delta = \{\{A, B, C\}, \{\neg A, \neg B\}, \{A, \neg C\}, \{\neg B, \neg C\}, \{\neg A, B\}, \{A, \neg B\}\}$.

Run DPLL to check if $\Delta$ is satisfiable. How often do you need to apply the splitting rule?