In one-word substitutions, a person who dies willingly for a noble cause, belief, or principle is called what?

Introduction / Context:
This vocabulary question focuses on a well-known one-word substitution from moral and historical contexts. Many stories, religious traditions, and freedom struggles speak of people who willingly sacrifice their lives for a noble cause or belief. English has a specific word for such a person, and this term appears frequently in reading passages and general knowledge content.

Given Data / Assumptions:

• The stem describes someone who dies for a noble cause.
• Martyr refers to a person who suffers or is killed because of their beliefs, especially religious or political ones.
• Pilgrim is a person who journeys to a holy place for religious reasons.
• Astronomer is a scientist who studies celestial objects like stars and planets.
• Pantomath is a rare term meaning a person who wants to know or knows everything.

Concept / Approach:
The key idea is voluntary sacrifice of life for some higher principle: faith, freedom, or justice. The standard English word for such a person is martyr. Pilgrims travel for worship but are not defined by dying for their cause. Astronomers and pantomaths belong to completely different areas (science and knowledge). Therefore, only martyr correctly captures the meaning in the question.

Step-by-Step Solution:
Step 1: Underline the phrase dies for a noble cause or belief in the question.Step 2: Recall that martyr is defined as a person who chooses to suffer or die rather than give up their principles or faith.Step 3: Consider pilgrim, which refers to a traveller to a holy place; the word does not require death or sacrifice.Step 4: Consider astronomer and pantomath and recognise that they are unrelated to sacrifice or noble causes.Step 5: Conclude that martyr is the only option matching the definition.

Verification / Alternative check:
Look at typical uses of the word in history: National heroes who have died in wars for independence are often called martyrs. Religious traditions speak of martyrs who accepted death rather than deny their faith. These uses align exactly with the phrase dies for a noble cause. Pilgrimages, on the other hand, are described using the word pilgrim, and the focus there is on travel, not death.

Why Other Options Are Wrong:
Pilgrim, while a religious term, does not inherently involve sacrifice of life. An astronomer studies astronomical phenomena and is purely a scientific profession. Pantomath, even though unusual, describes someone with very broad knowledge or a desire to know everything, not someone who sacrifices their life for a cause. Thus, options B, C, and D do not satisfy the given definition.

Common Pitfalls:
Students sometimes mix up religious words. They may see pilgrim and think of devotion, but the question clearly focuses on dying for a cause, not travelling. Another pitfall is to be distracted by rare or impressive-sounding words like pantomath. A good exam strategy is to first try to recall the simplest and most familiar term that matches the definition; in this case, martyr should come to mind quickly.

Final Answer:
A person who dies for a noble cause or belief is called a Martyr, so option A is correct.