Out of the four alternatives, choose the one word which best substitutes the given phrase: "The punishment of being kept in school after hours."

Introduction / Context:
One word substitution questions require the learner to replace a given phrase or description with a single precise term. This builds vocabulary and reduces wordiness in expression. In the context of schools, certain disciplinary actions have specific names. Knowing these terms helps in understanding school rules, novels, and administrative language that mention punishments or corrective measures.

Given Data / Assumptions:
The phrase to be replaced is: the punishment of being kept in school after hours. This clearly refers to a formal or informal penalty used in many educational institutions where a student must remain at school after regular classes. The options list different nouns and verbs. Our task is to pick the term that specifically refers to this educational punishment and not to some unrelated concept such as pretending or mixing.

Concept / Approach:
In English, the standard word for the punishment of being kept back at school beyond normal hours is detention. Many students are familiar with the phrase get detention. It precisely matches the idea described. We should examine whether any other option carries this meaning or whether they belong to different semantic fields. Only the term detention regularly appears in school conduct rules and parent teacher communications to describe this kind of disciplinary action.

Step-by-Step Solution:
Step 1: Restate the phrase: a school punishment where a student is required to stay after official school time.
Step 2: Recall any standard English term used for this practice.
Step 3: Identify detention as the commonly used word for this punishment.
Step 4: Check whether any alternative option describes the same idea. Notice that none do.
Step 5: Select detention as the one word substitute for the given phrase.

Verification / Alternative check:
In school handbooks and disciplinary policies, we often see statements such as Students who arrive late three times will receive detention for one hour after school. This usage directly matches the description in the question. The word is strongly associated with educational institutions and after hours punishment. No other choice in the list is used in this way. This confirms that detention is the accurate and accepted term.

Why Other Options Are Wrong:
Option A, pretension, relates to behaviour that is artificial or pretended, and has nothing to do with school punishment. Option B, isolate, is a verb meaning to separate from others, not a noun naming a specific type of penalty. Option D, blender, is a kitchen appliance used to mix foods and is clearly unrelated. Option E, exclusion, can mean keeping someone out, but it does not specifically convey the idea of making a student stay back in school after hours as punishment. Therefore these words are either in the wrong part of speech or do not capture the intended meaning.

Common Pitfalls:
Some candidates may guess from partial similarity of sound or general negativity without matching the phrase carefully. Others may forget that in one word substitution questions the grammatical category of the answer should usually match the function of the phrase, which here is a noun phrase. Knowing a range of school related vocabulary such as suspension, expulsion, detention, and warning helps avoid confusion and improves performance in vocabulary sections.

Final Answer:
The one word substitute for the punishment of being kept in school after hours is Detention.