If I'm not mistaken services generally fall under tertiary therefore communication should be in tertiary sector and others belongs to primary that's for sure, by using substitution method "D" must be correct for TS.

The tertiary sector, also known as the service sector, is the segment of the economy that provides services to the consumers. It includes a wide range of activities such as transportation, communication, finance, healthcare, education, and hospitality. The correct answer to the question is option D, communication, as it falls under the tertiary sector. Let's understand why communication is considered a part of the tertiary sector.

Communication as a Service:
- Communication refers to the exchange of information, ideas, and messages between individuals, organizations, or entities. It plays a crucial role in our daily lives and is essential for the functioning of businesses, governments, and societies.
- In today's digital age, communication services have become an integral part of the economy, providing various means of transmitting information and facilitating interactions between people.
- Communication services include telecommunication, internet services, broadcasting, postal services, and other means of transmitting information through different mediums such as telephone, mobile networks, internet, television, radio, and mail.

Key Role in Economic Development:
- Communication services contribute significantly to economic development by enabling the flow of information and supporting various sectors of the economy.
- Businesses rely on communication services for conducting transactions, marketing their products, managing supply chains, and coordinating operations.
- Communication services also facilitate trade and commerce by connecting businesses with customers, suppliers, and partners globally.
- The availability of reliable and efficient communication infrastructure is crucial for attracting investments, promoting innovation, and fostering economic growth.

Employment Generation:
- The communication sector creates employment opportunities by providing various services and technologies.
- It requires a skilled workforce to design, develop, operate, and maintain communication networks, software, and hardware.
- This sector also generates jobs in customer service, technical support, content creation, journalism, broadcasting, and other related fields.
- Employment opportunities in the communication sector contribute to the overall employment rate and provide income-generating opportunities for individuals.

Conclusion:
In conclusion, communication is an essential part of the tertiary sector. It plays a crucial role in facilitating the exchange of information, supporting economic activities, and generating employment opportunities. The development and availability of communication services are vital for the functioning and growth of businesses, governments, and societies.