In the following one word substitution question, select the alternative that best replaces the phrase "killer of prophet", that is, a person who kills a prophet.

Introduction / Context:
One word substitution questions test your knowledge of precise English vocabulary for specific roles, actions, or relationships. In this item, you are asked to choose the single word that means "killer of prophet". Such words often come from Latin roots and appear in advanced vocabulary lists for competitive exams and language proficiency tests.

Given Data / Assumptions:

• The phrase to be replaced is "killer of prophet".
• You must choose from four words that all end with "-cide", meaning killing.
• Each option refers to killing a specific type of person.
• You are expected to know or deduce the correct root corresponding to "prophet".

Concept / Approach:
The suffix "-cide" comes from the Latin "caedere", meaning to kill. The prefix tells you who or what is killed. For example, "patri" refers to father, so "patricide" is killing one s father. "Mari" refers to husband, so "mariticide" is killing one s husband. "Sorori" refers to sister, so "sororicide" is killing one s sister. The Latin root "vates" means prophet or seer, so "vaticide" is the killing of a prophet. The correct option must match this root meaning.

Step-by-Step Solution:
Step 1: Recognise that all options share the suffix "-cide", indicating an act of killing. Step 2: Focus on the prefixes to see what type of victim each word refers to. Step 3: Recall that "pater" or "patri" refers to father, "maritus" to husband, "soror" to sister, and "vates" to prophet. Step 4: Match "vates" (prophet) with the option "Vaticide". Step 5: Confirm that none of the other options refer to a prophet, making "Vaticide" the only correct choice.

Verification / Alternative check:
If you know other related words, you can verify your answer by comparison. For example, "homicide" is killing a human, "suicide" is killing oneself, and "genocide" is mass killing of a people. In the same way, "vaticide" logically fits with the idea of killing a prophet or seer. Cross checking with the roots of the other options confirms that they relate to different family members rather than prophets, which supports the selection of Option B.

Why Other Options Are Wrong:

• Option A, "Mariticide", means the killing of one s husband and is derived from "maritus" (husband), not a prophet.
• Option C, "Patricide", refers to killing one s father and comes from "pater" (father).
• Option D, "Sororicide", means killing one s sister and is formed from "soror" (sister).

Common Pitfalls:
Candidates sometimes choose the wrong option simply because they recognise the "-cide" ending and guess without paying attention to the prefix. Another common mistake is to rely only on similarity to a familiar English word without analysing the Latin root. To improve accuracy in one word substitution questions, it is helpful to learn the most common Latin and Greek roots, especially those relating to family relationships, professions, and actions. This enables you to quickly decode unfamiliar words in an exam setting.

Final Answer:
The one word substitution for "killer of prophet" is Vaticide, so Option B is correct.