Postal network is the largest communication service in India and in the world. Here's an explanation of why this is the correct answer:

1. Importance and Reach of Postal Services:
- Postal services have been an integral part of communication infrastructure for centuries. They have played a crucial role in connecting people, businesses, and governments across vast distances.
- India has one of the largest and most extensive postal networks in the world, with over 1.5 lakh post offices spread across the country. This vast network ensures that postal services reach even the remotest corners of the country, including rural areas where other communication services may not be as accessible.

2. Wide Range of Services:
- The postal network offers a wide range of services, including sending letters, parcels, money orders, and even providing banking facilities through post offices.
- India Post, the national postal service provider, offers various services like Speed Post, Registered Post, Express Parcel Post, and more. These services cater to the diverse needs of individuals, businesses, and government organizations.

3. Large Workforce:
- The postal network in India employs a significant number of people, making it one of the largest employers in the country. This workforce ensures the smooth functioning of postal services and timely delivery of mail and packages.
- The vast reach of postal services also contributes to employment generation in rural areas, where post offices act as important sources of employment.

4. Role in Financial Inclusion:
- In a country like India, where access to banking services is limited in rural areas, post offices play a crucial role in promoting financial inclusion. They provide basic banking services, such as savings accounts, recurring deposits, and money transfers, making banking accessible to a larger population.

5. Integration of Technology:
- Over the years, the postal network in India has embraced technology to enhance its services. It offers online tracking facilities for parcels, e-commerce services, and digital payment options, keeping pace with the changing communication needs of the modern era.

In conclusion, the postal network in India is the largest communication service in the world due to its extensive reach, wide range of services, large workforce, role in financial inclusion, and integration of technology. It remains an essential and reliable mode of communication for millions of people in India, especially in areas where other communication services may not be as prevalent.