The correct answer is option 'B' - Idukki dam.

Explanation:
Arch dams are curved structures that are designed to curve upstream and resist the water pressure by transferring it to the abutments or the valley sides. They are commonly used to create large reservoirs and are known for their strength and stability.

Let's take a closer look at the options:

a) Tehri dam: Tehri dam is a multi-purpose rock and earth-fill embankment dam located on the Bhagirathi River in Uttarakhand. It is not an arch dam as it is constructed using embankment techniques.

b) Idukki dam: Idukki dam is an arch dam built across the Periyar River in Kerala. It is one of the largest arch dams in Asia. The dam is constructed using concrete and masonry and has a double curvature. It is a classic example of an arch dam.

c) Bhakra dam: Bhakra dam is a concrete gravity dam located on the Sutlej River in Himachal Pradesh. It is not an arch dam as it is constructed using the gravity dam technique.

d) Sardar Sarovar dam: Sardar Sarovar dam is a concrete gravity dam built on the Narmada River in Gujarat. Similar to Bhakra dam, it is not an arch dam.

In conclusion, among the given options, only the Idukki dam is an example of an arch dam. It is important to note that arch dams are known for their strength and ability to withstand high water pressure. They are designed to curve upstream, allowing the water pressure to be directed to the abutments or the valley sides, providing stability to the dam structure.