Explanation : In an operating system, indivisibility of operation means processor can not be pre-empted. One a process starts its execution it will not suspended or stop its execution inside the processor. So, option (C) is correct.
Explanation : In logic programming horn clause is a clause that has at most one positive literal. When there is exactly one positive literal then it is known as definite clause but when there is no positive literal then sometimes it is called goal clause. So, option (D) is correct.
Explanation : The rule of inference logic which states that if a conditional statement (‘if p then q’) is accepted, and the antecedent (p) holds (i.e. P and P → Q), then the consequent (q) may be inferred. For more information on inference logic Refer:Mathematics | Rules of Inference Option Q is correct.
Explanation : Reasoning strategies used in expert systems include forward chaining, backward chaining and problem reduction. In Forward chaining expert system is driven by antecedent and backward system is driven by consequent. So, option (A) is correct.