In the following question, from the given alternative words, select the word which cannot be formed using the letters of the given word: NIGHTWALKER.

Introduction / Context:
This is a word-formation question based on letter availability. You are given one base word and several option words. The task is to decide which option word cannot be formed using the letters of the base word, where each letter of the base word can be used only as many times as it actually appears. Such questions test attention to detail and counting skills more than vocabulary knowledge.

Given Data / Assumptions:
- Base word: NIGHTWALKER.
- Options: Talker, Tailer, Waller, Winer.
- Each letter in NIGHTWALKER can be used at most once per occurrence in that word.
- We assume standard English letter counts, ignoring case (treating all letters as uppercase or lowercase uniformly).

Concept / Approach:
The method is straightforward:
- First, list the letters in the base word along with their frequencies.
- Then, for each option word, check whether every required letter exists in the base word in at least the same quantity.
- If any letter in the option requires more copies than available, that option cannot be formed and is therefore the answer.

Step-by-Step Solution:
Step 1: Write the letters of NIGHTWALKER: N, I, G, H, T, W, A, L, K, E, R. Step 2: Count frequencies: N(1), I(1), G(1), H(1), T(1), W(1), A(1), L(1), K(1), E(1), R(1). Every letter appears exactly once. Step 3: Check “Talker”: letters T, A, L, K, E, R. Each of these letters appears at least once in NIGHTWALKER, and none is repeated beyond the available count. So “Talker” can be formed. Step 4: Check “Tailer”: letters T, A, I, L, E, R. Again, each letter is present once in NIGHTWALKER, so “Tailer” can be formed. Step 5: Check “Waler” with an extra L to get “Waller”: letters W, A, L, L, E, R. Here the letter L appears twice, but NIGHTWALKER contains L only once. Therefore there are not enough Ls to spell “Waller”. Step 6: Check “Winer”: letters W, I, N, E, R. All of these letters exist once in the base word, so “Winer” can be formed.

Verification / Alternative check:
We can summarise quickly: the only problematic option is “Waller”, which demands two copies of L. Since the base word has just one L, forming “Waller” is impossible. All other options require each letter only once and match the available counts exactly.

Why Other Options Are Wrong:
- “Talker”: All letters (T, A, L, K, E, R) appear once each in NIGHTWALKER, so this word is formable.
- “Tailer”: All letters (T, A, I, L, E, R) are present and used only once, so it is also formable.
- “Winer”: Composed of W, I, N, E, R, each of which is available in the base word, so it can be formed.

Common Pitfalls:
The main mistake is to check only whether the letters occur at all and forget to check how many times they occur. Many learners see that L exists in NIGHTWALKER and assume it is enough, ignoring that “Waller” needs two Ls. Another pitfall is reading too fast and miscounting letters like N and M or confusing similar shapes. Always slow down, count carefully, and compare frequencies.

Final Answer:
The word that cannot be formed from the letters of NIGHTWALKER is “Waller” because it requires two Ls while the base word has only one.