Final answer:
The correct conclusion that follows from the given premises is G ⊃ A (option a). This can be determined through the use of Disjunctive Syllogism, Simplification, and Modus Ponens.
Step-by-step explanation:
The correct conclusion that follows in a single step from the given premises is G ⊃ A (option a).
To arrive at this conclusion, we need to use Disjunctive Syllogism. Starting with premise 1 (G ⊃ A) ∨ ~T, we can eliminate the second disjunct (~T) because it is not relevant to our goal of determining the conclusion. This leaves us with (G ⊃ A). From premise 2 (G), we can use Simplification to derive G. Then, combining G with (G ⊃ A), we can use Modus Ponens to conclude A.