One word substitution – a person who is always dissatisfied.

Introduction / Context:
One word substitution questions ask you to replace a whole descriptive phrase with a single precise term. Here the phrase is a person who is always dissatisfied. This describes a personality type that is never happy with circumstances, authority, or the system. The question checks your ability to recall the correct English noun for this sort of chronic dissatisfaction.

Given Data / Assumptions:

We need a noun that labels a type of person, not an action or idea.
The key idea is constant dissatisfaction, not just occasional unhappiness.
Some options represent very different concepts, such as crime or religious offence.
The correct word is used in social and political discussions about unhappy citizens or employees.

Concept / Approach:
The noun malcontent is used for a person who is habitually dissatisfied and frequently complains or rebels. It can describe individuals or groups who are unhappy with the existing order and express their discontent. In contrast, surrogate refers to a substitute, heresy refers to a controversial belief, felon refers to a person guilty of a serious crime, and altruist refers to someone who is unselfish and helps others. Only malcontent matches the idea of someone who is always dissatisfied.

Step-by-Step Solution:
Step 1: Focus on the key phrase always dissatisfied, which suggests a lasting, habitual attitude rather than a temporary feeling. Step 2: Recall that malcontent is commonly defined as a person who is discontented and often complains or rebels. Step 3: Check option A malcontent and see that it fits both the idea of dissatisfaction and the requirement that the word be a noun for a person. Step 4: Examine option B surrogate, which means a substitute or replacement, such as a surrogate mother; this is unrelated to dissatisfaction. Step 5: Look at option C heresy, which names a belief that goes against accepted doctrine, especially in religion, not a type of person. Step 6: Option D felon labels a serious criminal, and option E altruist refers to a selfless person who cares for others, neither of which expresses the idea of constant discontent.

Verification / Alternative check:
Consider a sentence like The government struggled to satisfy the demands of the malcontents. Here malcontents clearly refers to people who are not satisfied with the government. Replacing malcontents with surrogates or felons would not make sense in that context. Similarly, describing a helpful volunteer as a malcontent would be wrong, but calling them an altruist fits perfectly. These quick tests confirm that malcontent is the only candidate that preserves the meaning of always dissatisfied.

Why Other Options Are Wrong:
Option B surrogate describes someone or something that acts in place of another, such as a substitute teacher, and has nothing to do with satisfaction level.
Option C heresy names an idea or belief that goes against accepted doctrine, not a person who is always unhappy.
Option D felon labels a person guilty of a serious crime, which is about law and punishment, not mood or attitude.
Option E altruist refers to a person who puts others needs before their own, often in a generous and caring way, which is unrelated to continuous dissatisfaction.

Common Pitfalls:
Exam takers sometimes focus only on whether an option refers to a person and ignore the qualifying description. Both felon and altruist refer to people, but they completely miss the specific trait of constant dissatisfaction. Always read the full phrase carefully and look for a word that matches every part of the description, not just the fact that the answer must be a noun.

Final Answer:
The one word for a person who is always dissatisfied is malcontent.