Step 1: Check Assertion (A) alone: combining teaching methods is standard, effective extension practice, so it is true.
Step 2: Check Reason (R) alone: varied presentation suits different learning styles and speeds up understanding, so it is also true.
Step 3: Ask whether (R) answers why (A) works: yes, reaching learners through multiple channels is exactly why combining methods helps.
Step 4: Both are true and (R) explains (A), so the correct option is (1).