Which of the following is true in regards to development of infrastructure?

1. It means proper installation of electrical wires, various irrigation facilities etc.
2. It does not include credit marketing and financial assistance.
3. Infrastructural development promotes agricultural research and extension.

1 and 3

The correct answer is option 3: 1 and 3

Here's a breakdown of why:

Proper installation of electrical wires, various irrigation facilities, etc.: This is a core component of infrastructure development. It ensures essential services and facilities are available to support economic activities.

Credit marketing and financial assistance: While these are important for economic development, they are not typically considered part of infrastructure development itself. 

Infrastructural development promotes agricultural research and extension: Improved infrastructure, such as better roads, transportation, and communication facilities, can facilitate the dissemination of agricultural knowledge and research, leading to better farming practices and increased productivity.