Step 1: Understanding the Concept:
Extension methods are classified based on the number of people they are designed to reach.
These categories are: individual contact, group contact, and mass contact methods.
Step 2: Detailed Explanation:
Let us analyze each of the extension tools listed:
(A) Personal letter:
This is a direct, written communication sent to a single individual.
Thus, it is classified as an Individual Contact method.
Hence, (A) matches with (III).
(B) Method demonstration:
This involves showing a specific group of people how to perform a practical skill (e.g., how to treat seeds or use a modern tool).
Since it is designed for a small group of learners with shared interests, it is classified as a Group Contact method.
Hence, (B) matches with (IV).
(C) Television:
This is a broadcast medium that reaches a very large, diverse, and geographically scattered audience simultaneously.
Thus, it is classified as a Mass Contact method.
Hence, (C) matches with (II).
(D) Campaign:
A campaign is an intensive, coordinated effort designed to motivate an entire community to adopt a specific practice (e.g., a sanitation or vaccination drive).
Its primary goal is mass mobilization.
Hence, (D) matches with (I).
Step 3: Final Answer:
Matching the methods with their purposes gives:
(A) - (III), (B) - (IV), (C) - (II), (D) - (I).
This matches Option (C).