In this analogy question, the pair Pesticide : Plant is given. A pesticide is a substance used to protect a plant from harm by killing or controlling pests. From the options below, choose the pair of words that shows the most similar relationship to the relationship between pesticide and plant.

Introduction / Context:
Analogy questions in English and general aptitude test your ability to recognise relationships between pairs of words. Here, the base pair Pesticide : Plant describes an agent and the thing it is meant to protect. A pesticide is applied so that a plant remains healthy and safe from harmful pests. The goal is to identify which option expresses a similar protective relationship between two items.

Given Data / Assumptions:
- Pesticide is a chemical agent. - Plant is the living thing that the pesticide is meant to protect. - We must select the option where the first word protects or safeguards the second in a similar preventive or protective way.

Concept / Approach:
To solve analogy questions, first clearly describe the relationship in the given pair in simple language. Here, a pesticide is used as a preventive measure to protect a plant from pests and diseases. It is not the plant itself but something applied to the plant. Next, examine each option and test whether the first word is a preventive or protective measure that is used on or for the second word, similar to pesticide for a plant. The pair with the closest conceptual match is the correct answer.

Step-by-Step Solution:
Step 1: Pesticide : Plant means a chemical agent used on a plant to protect it from harmful organisms. Step 2: Injection : Disease suggests that an injection is a tool to treat a disease, not the thing that is protected. The disease is not protected, so this is not a close match. Step 3: Vaccination : Body shows a preventive agent that is given to the human body to protect it from future infections. This is very similar to pesticide protecting a plant. Step 4: Medicine : Cure is not parallel because medicine is used to bring about a cure, and the cure is a result, not a thing being protected. Step 5: Teacher : Student shows a human relationship of guidance and education, not a substance that protects a physical entity.

Verification / Alternative check:
A quick check is to restate each option in the form first word protects the second word. Only vaccination protects the body in a preventive way comparable to pesticide protecting the plant. Injection can deliver many things including painkillers or saline and is not directly the counterpart of pesticide. Medicine helping a cure is a different kind of relationship, and teacher guiding student is yet another relationship type. Therefore, the best and closest match remains vaccination protecting the body.

Why Other Options Are Wrong:
Option A is wrong because injection is a method of delivering substances and disease is not something that is protected by an injection. Option C is wrong because medicine brings about a cure rather than protecting the cure itself. Option D is wrong because a teacher guides a student, which is a human relationship and not a chemical preventive relationship.

Common Pitfalls:
A common mistake is to choose an option that vaguely feels related to health or treatment without checking the precise direction of the relationship. Students may also confuse treatment with prevention. Remember that pesticide is primarily preventive, just as vaccination is preventive. Training yourself to express the relationship in words first, such as agent protects target, will make these questions much easier to handle in competitive exams.

Final Answer:
The pair with the same relationship as pesticide and plant is Vaccination : Body.