Indus Towers and Bharti Infratel have agreed to combine operations in a deal that will create the world's second-largest mobile masts company measured by numbers of towers. The correct answer is option 'C' - Bharti Infratel.

Explanation:
- Indus Towers is a telecommunications infrastructure company based in India. It is a joint venture between Bharti Infratel, Vodafone, and Idea Cellular (now merged with Vodafone).
- Bharti Infratel is a subsidiary of Bharti Airtel, one of India's largest telecommunications companies. It is engaged in the business of providing passive telecom infrastructure to telecom operators.
- The deal between Indus Towers and Bharti Infratel involves merging their operations to create a single entity. This merger will result in the formation of the world's second-largest mobile masts company in terms of the number of towers owned.
- The combined entity will have a vast network of mobile towers spread across India, providing infrastructure support to various telecom operators in the country.
- The deal is significant as it will enable the merged entity to leverage synergies and optimize operational efficiencies. It will also strengthen the position of the merged company in the highly competitive telecom infrastructure market.
- The merger is expected to benefit both Indus Towers and Bharti Infratel in terms of increased scale, improved financial performance, and enhanced market share.
- The merger is subject to regulatory approvals and is expected to be completed in a timely manner.
- The creation of the second-largest mobile masts company will have a significant impact on the telecommunications industry, as it will provide a strong alternative to existing players and foster healthy competition.
- This development reflects the ongoing consolidation in the telecom sector, as companies strive to enhance their capabilities and expand their reach in a rapidly evolving market.

In conclusion, the deal between Indus Towers and Bharti Infratel to combine operations will create the world's second-largest mobile masts company. This merger is expected to bring several benefits to both companies and contribute to the overall growth and competitiveness of the telecommunications industry in India.