From the given options, select the word that cannot be formed using the letters of the word THREATENED.

Introduction / Context:
This word formation question uses the base word THREATENED. Your task is to pick the option that cannot be formed from its letters. The test focuses on how accurately you can match letters, detect missing ones, and ensure that the number of occurrences of each letter does not exceed what is available. These skills are essential in verbal ability sections of competitive exams, where small oversights can lead to incorrect answers.

Given Data / Assumptions:
Base word: THREATENED.
Letters available: T, H, R, E, A, T, E, N, E, D.
Options: Heart, Detain, Treat, Heated.
We assume case insensitivity and that each letter in the base word may be used at most as many times as it appears there.

Concept / Approach:
The strategy is to list the letters and their counts from THREATENED and then check each option. If an option contains any letter that is absent in the base word, or uses some letter more frequently than allowed, it cannot be formed. Detecting such discrepancies quickly is the heart of solving this kind of problem. We will go option by option to identify the invalid one.

Step-by-Step Solution:
Step 1: Count the letters in THREATENED. T: 2, H: 1, R: 1, E: 3, A: 1, N: 1, D: 1. Step 2: Check Heart. Heart requires H, E, A, R, T. All these letters are present in THREATENED within the available counts, so Heart can be formed. Step 3: Check Treat. Treat requires T, R, E, A, T. The base word has T twice, R once, E three times and A once, so Treat can also be formed. Step 4: Check Heated. Heated requires H, E, A, T, E, D. THREATENED has H once, E three times, A once, T twice and D once. This is enough to form Heated, so Heated is valid. Step 5: Check Detain. Detain requires D, E, T, A, I, N. The base word THREATENED has D, E, T, A and N, but it does not contain the letter I. Therefore Detain cannot be formed from THREATENED.

Verification / Alternative check:
To verify, scan the letters of THREATENED once more: T, H, R, E, A, T, E, N, E, D. The absence of I is clear. Since Detain needs I, it is impossible to construct it from the base word. For Heart, Treat and Heated, each required letter appears in the base word and does not exceed the available counts. This shows that there is exactly one invalid option, confirming that Detain is the correct answer.

Why Other Options Are Wrong:
Heart is valid because H, E, A, R and T can be taken from THREATENED without violating frequency limits.
Treat is valid since both Ts, the R, E and A all occur with sufficient counts in the base word.
Heated is valid as well, because H, two Es, A, T and D are all available within the existing letter counts.
These words therefore can be formed and do not meet the requirement of being impossible to construct from THREATENED.

Common Pitfalls:
A common error is to overlook a single letter like I, especially when most of the other letters match. Examinees may see that D, E, T, A and N are present and quickly assume that Detain is valid without checking for I. Under time pressure, it is easy to miss this subtle detail. To avoid such mistakes, always scan each option for letters that are completely absent from the base word before performing detailed frequency checks. This simple habit significantly improves accuracy in word formation questions.

Final Answer:
The word that cannot be formed using the letters of THREATENED is Detain, because it requires the letter I, which is not present in the base word.