Final answer:
Using disjunctive syllogism, we can deduce that if we have a disjunction (T or S) and one part (not T) is negated, then S must be true. Hence, the correct answer is d. S 1, 3, DS.
Step-by-step explanation:
The question from the student is asking us to identify the conclusion that follows in a single step from the given premises. The premises provided are:
- T ∨ S (T or S)
- A ⊕ T (If A then T)
- A • (¬T • S) (A and not T and S)
Based on the provided premises and rules of logical inference, we can determine the correct conclusion. The correct answer to the question is d. S 1, 3, DS. This is because using the rule of disjunctive syllogism (DS), we can deduce that if we have a disjunction (T or S) and we know that one part of the disjunction cannot be true (not T, as from the third premise), S must be true.