In India, which organisation is responsible for preparing official topographical maps of the country?

Introduction / Context:
Topographical maps show detailed physical and cultural features of the land, such as elevations, rivers, roads and settlements. In India, the preparation of these maps is the responsibility of a specific national organisation. Knowing which government body performs this function is a straightforward but important part of geography and general knowledge tested in many exams.

Given Data / Assumptions:

• The question is about topographical maps covering India.
• Options include the Defence Ministry, Geological Survey of India, Survey of India, and a fictitious sounding Geographical Survey of India.
• We assume candidates are familiar with the names of key scientific and mapping institutions of the country.

Concept / Approach:
Different organisations handle different aspects of mapping and earth science. Geological Survey of India focuses on geological resources like minerals and rock formations. Survey of India is the national mapping agency responsible for surveying and mapping the country, including the creation of topographical sheets. Defence-related agencies may use maps, but they are not the official civil mapping authority. By understanding each body's mandate, the correct choice can be identified easily.

Step-by-Step Solution:
Step 1: Recall that the Survey of India is India's oldest scientific department and is tasked with mapping and surveying the country. Step 2: Topographical maps are detailed survey maps with contours, heights, and man made features, which fall squarely under the responsibility of a survey organisation rather than a specialised geological department. Step 3: Understand that Geological Survey of India focuses more on geology, such as mineral exploration and rock studies, not on producing standard topographical sheets for general use. Step 4: Recognise that the option Geographical Survey of India is not the name of an actual central organisation, making it a distractor. Step 5: Conclude that Survey of India is the correct organisation responsible for official topographical maps.

Verification / Alternative check:
Verification can be done by remembering the heading found on many old school atlases and official map sheets that clearly state "Survey of India" on the margin. In school geography, the exercise on reading topographical sheets also refers to maps produced by Survey of India, confirming that it is the national mapping agency for topographical work.

Why Other Options Are Wrong:
Defence Ministry: The ministry may use maps for strategic purposes but is not the primary civil mapping agency producing public topographical maps.
Geological Survey of India: This body deals with earth science and geological surveys, focusing on minerals, rocks and structures rather than comprehensive topographical mapping for general use.
Geographical Survey of India: This is not the official name of any central institution and appears only as a decoy to confuse candidates who do not recall the exact names.

Common Pitfalls:
One common pitfall is confusing Survey of India with Geological Survey of India because both contain the word "Survey". Another mistake is assuming that the Defence Ministry must control all important maps due to security concerns. Candidates should remember that while security agencies use maps, a separate professional survey organisation performs the actual mapping task.

Final Answer:
The organisation responsible for preparing official topographical maps of India is the Survey of India.