Which one of the following statements correctly describes a formation within the Indian Army?

Introduction / Context:
The Indian Army has a complex organisational structure with various arms and services performing specialised roles. General knowledge about which corps and regiments exist, and how they are grouped, is frequently tested in defence related examinations. This question asks which one of the given statements correctly describes a formation within the Indian Army. To answer, you must know the distinct identities of infantry, mechanised infantry, technical corps and support services.

Given Data / Assumptions:

• Option A equates the Infantry Regiment with the Mechanized Infantry Regiment.
• Option B claims that the Corps of Electrical and Mechanical Engineers is part of the Corps of Engineers.
• Option C suggests that Army Medical Corps and Army Dental Corps are divisions of the Army Service Corps.
• Option D states that the Indian Army has its own Corps of Air Defence.
• Only one of these statements is correct.

Concept / Approach:
The approach is to evaluate each statement against the actual organisation of the Indian Army. Infantry and Mechanized Infantry are separate arms, not the same regiment. The Corps of Electrical and Mechanical Engineers is a distinct corps responsible for technical maintenance and is not subsumed under the Corps of Engineers, which deals with combat engineering tasks. Army Medical Corps and Army Dental Corps are separate medical services, not divisions of the Army Service Corps, which focuses on supply and logistics. However, the Indian Army does have a dedicated Air Defence arm known as the Army Air Defence, sometimes referred to as the Corps of Army Air Defence. Therefore, the correct statement is the one referring to this corps.

Step-by-Step Solution:
Step 1: Analyse Option A. Infantry units are foot soldiers, and Mechanized Infantry is a separate arm equipped with armoured vehicles. They are different arms with distinct structures, so this statement is incorrect. Step 2: Analyse Option B. The Corps of Electrical and Mechanical Engineers is a separate corps dealing with repair and maintenance of equipment and is not a subset of the Corps of Engineers, which focuses on engineering tasks such as bridge building and demolitions. Therefore, this statement is false. Step 3: Analyse Option C. Army Medical Corps and Army Dental Corps are medical services that provide health care, whereas the Army Service Corps handles supplies, transport and logistics. They are not divisions of the Army Service Corps, so this statement is incorrect. Step 4: Analyse Option D. The Indian Army has its own dedicated Air Defence arm, called Army Air Defence, which is organised as a separate corps. This statement correctly reflects the existence of a Corps of Air Defence within the army. Step 5: Conclude that Option D is the only correct statement.

Verification / Alternative check:
An alternative check is to recall the broad classification of arms and services in the Indian Army. Arms include Infantry, Armoured Corps, Artillery, Army Air Defence and Engineers, among others. Services include Army Service Corps, Army Medical Corps, Army Dental Corps and Corps of Electrical and Mechanical Engineers. Mechanized Infantry is treated as a distinct arm, while the Corps of Electrical and Mechanical Engineers is grouped as a technical service rather than as part of the engineering arm. This overview confirms that Option D alone accords with the established organisational reality.

Why Other Options Are Wrong:

• Infantry Regiment is also known as the Mechanized Infantry Regiment: This conflates two separate arms and ignores their different roles and equipment.
• Corps of Electrical and Mechanical Engineers is subsumed in the Corps of Engineers: This misrepresents the structure; they are two separate corps with different tasks.
• Army Medical Corps and Army Dental Corps are two divisions of the Army Service Corps: This incorrectly subsumes medical services under a logistics corps.

Common Pitfalls:
A common mistake is to assume that all technical and support functions are grouped into a few large corps, which leads to merging distinct entities like Engineers and Electrical and Mechanical Engineers. Another pitfall is to overlook the existence of a dedicated Army Air Defence arm and to think that all air defence is handled only by the Air Force. Careful study of the official list of arms and services can prevent such misunderstandings.

Final Answer:
The correct description is that the Indian Army has its own dedicated Corps of Air Defence, corresponding to Option D.