Which of the below given series is Non-Increasing Order −

A sequence is said to be in Non-Increasing Order when every successive term is less than or equal to the term before it — that is, for consecutive terms a(i) and a(i+1), the condition a(i) ≥ a(i+1) must hold throughout the sequence. Equal consecutive terms are allowed; the only thing that is NOT allowed is a later term being strictly greater than an earlier one.

Checking the correct series term by term:

1. Check 9 to 8: 9 ≥ 8, holds.

2. Check 8 to 6: 8 ≥ 6, holds.

3. Check 6 to 3: 6 ≥ 3, holds.

4. Check 3 to 3: 3 ≥ 3, holds (equal values are permitted in a non-increasing sequence).

5. Check 3 to 1: 3 ≥ 1, holds. Every consecutive pair satisfies the non-increasing condition, so this series qualifies.

Contrast with the other series:

• 1, 3, 4, 6, 8, 9 — every term is strictly greater than the one before it, so this is an increasing series, the opposite of what is required.

• 9, 8, 6, 3, 4, 1 — the terms fall from 9 to 3, but then rise from 3 to 4 before falling again to 1; that single rise breaks the non-increasing condition.

• 1, 3, 3, 6, 8, 9 — every term is greater than or equal to the one before it, so this is a non-decreasing series, the reverse pattern of a non-increasing one.