Among the given options, the Union Territory of Chandigarh shares the shortest length of National Highways. National Highways are an important transportation network in India, connecting different parts of the country.

Option 1: Chandigarh is a Union Territory located in northern India. It is the capital of both Punjab and Haryana states. Chandigarh has a well-planned road infrastructure, but it has a relatively shorter length of National Highways compared to other Union Territories.

Option 2: Delhi is the capital of India and also a Union Territory. It has a well-developed road network, including National Highways. However, it does not share the shortest length of National Highways among the given options.

Option 3: Daman and Diu is a Union Territory located on the western coast of India. While it has a small land area, it does not have a significant length of National Highways.

Option 4: Dadra and Nagar Haveli is also a Union Territory situated in western India. It is surrounded by Gujarat state. Although it has some National Highways passing through it, it is not the Union Territory with the shortest length of National Highways.

In summary, among the given options, option 1, Chandigarh, is