A simple decreasing alphabet series is given: Q, P, O, N, ?. Which letter of the English alphabet should replace the question mark to continue this pattern correctly?

Introduction / Context:
This question presents a straightforward alphabetical series in reverse order: Q, P, O, N, ?. We must determine which letter comes next. Such problems test very basic familiarity with the sequence of English letters and the ability to recognise simple decreasing patterns. They are often categorised as easy level questions in alphabet tests.

Given Data / Assumptions:

• Existing series: Q, P, O, N.
• The letters are consecutive in reverse alphabetical order.
• We are required to find the next letter after N when following the same pattern.
• Options: M, L, O, J.

Concept / Approach:
The concept is to observe whether the series moves forward (A to Z) or backward (Z to A) in the alphabet. Once the direction is identified, we simply continue the sequence by one step. Since each term is a single letter, there is no additional complexity or wrap around consideration here.

Step-by-Step Solution:
Step 1: List the letters with their positions: Q(17), P(16), O(15), N(14).Step 2: Observe that each term is one position less than the previous one, that is 17, 16, 15, 14.Step 3: The sequence therefore decreases by 1 at each step.Step 4: The next position after 14, when continuing this pattern, is 13.Step 5: The letter with position 13 in the English alphabet is M.Step 6: Hence, M should replace the question mark in the series.

Verification / Alternative check:
We can verify by writing out the local segment of the alphabet: M, N, O, P, Q. Reading it from right to left gives Q, P, O, N, M, which matches the given series with M as the next letter. None of the other options fits the simple step of minus one from N(14) because O is 15, L is 12, and J is 10.

Why Other Options Are Wrong:
Option O would reverse the decreasing pattern and go back to 15 instead of moving further down to 13. L and J are not immediate predecessors of N; they involve larger backward steps and therefore do not respect the exact pattern of subtracting 1 from the previous letter position.

Common Pitfalls:
Because the question is simple, some test takers overthink it or accidentally count the alphabet positions incorrectly. Others may confuse the direction and think in the forward sequence. Ensuring that the observed pattern is a consistent decrement of one position helps prevent such errors.

Final Answer:
The next letter in the series is M.