Step 1: Veneer and stone grafting are proven, high-success mango propagation methods, so (A) is true.
Step 2: Mango scion sticks stay usable for 5-6 days when properly stored, so (R) is true.
Step 3: This durability is exactly what makes long-distance grafting operations practical, linking (R) directly to (A).
Step 4: Correct answer: Both (A) and (R) are correct and (R) is the correct explanation of (A).