From the given alternative words, select the single word which cannot be formed using the letters of the word INTROSPECTION. Each letter from the base word may be used only as many times as it appears there.

Introduction / Context:
This word formation question uses the base word INTROSPECTION. You must determine which option cannot be constructed from its letters. The task evaluates your attention to detail in spellings and your ability to see quickly whether a letter is missing or overused.

Given Data / Assumptions:

• Base word: INTROSPECTION.
• Options: INSPECTION, SCOPE, SECTOR, ROUTE, POINTS.
• No new letter that is not present in INTROSPECTION may be used.
• Letters cannot be used more times than they appear in the base word.
• All words are in standard English spelling.

Concept / Approach:
The systematic method is:

• List the letters of INTROSPECTION and count each letter.
• For every option, check that each letter exists in the base word.
• Compare the counts for repeated letters and ensure they do not exceed what is available.
• Any option that requires a missing or overused letter cannot be formed.

Step-by-Step Solution:
Step 1: Write out INTROSPECTION: I, N, T, R, O, S, P, E, C, T, I, O, N. Step 2: Count the letters. We have I = 2, N = 2, T = 2, R = 1, O = 2, S = 1, P = 1, E = 1, C = 1. Step 3: Check INSPECTION. It needs I, N, S, P, E, C, T, I, O, N. This requires I = 2, N = 2, S = 1, P = 1, E = 1, C = 1, T = 1, O = 1. All of these are available within the base word counts, so INSPECTION can be formed. Step 4: Check SCOPE. It needs S, C, O, P, E. Each of these letters appears at least once in INTROSPECTION. None is overused, so SCOPE can be formed. Step 5: Check SECTOR. It needs S, E, C, T, O, R. The base word contains each of these and the counts are sufficient, so SECTOR can be formed. Step 6: Check POINTS. It needs P, O, I, N, T, S. The base word has P = 1, O = 2, I = 2, N = 2, T = 2, S = 1, so POINTS can also be formed. Step 7: Check ROUTE. It needs R, O, U, T, E. The letter U does not appear at all in INTROSPECTION. Because U is missing, it is impossible to form ROUTE from the base word.

Verification / Alternative check:
The quickest exam check is to scan for letters that do not exist in INTROSPECTION. All letters of INSPECTION, SCOPE, SECTOR, and POINTS can be spotted within the base word. However, U in ROUTE is absent. This immediately guarantees that ROUTE cannot be formed, without the need for more detailed counting.

Why Other Options Are Wrong:
INSPECTION uses letters I, N, S, P, E, C, T, and O, all present within the allowed counts. SCOPE uses S, C, O, P, and E, which are available in INTROSPECTION. SECTOR uses S, E, C, T, O, and R, all present and not overused. POINTS uses P, O, I, N, T, and S, all of which have sufficient counts in the base word.

Common Pitfalls:
Candidates sometimes check only a portion of an option word or miss a single letter like U. Another typical error is to assume that long options like INSPECTION are less likely to be formable, when in fact they can be carefully constructed from the base word. A quick scan for missing letters and then a short count check resolves such problems reliably.

Final Answer:
The word that cannot be formed from INTROSPECTION is ROUTE, because the letter U is not present in the base word.