The correct answer is: d) Scientific phenomena.
Tsomgo (Changu) Lake is a glacial lake in East Sikkim, India. It is located at an altitude of 3,710 meters (12,170 feet) and is the largest lake in Sikkim. The lake is known for its changing colors, which are caused by the reflection of the sky and the surrounding mountains. The lake is also associated with a number of legends and myths, including one that says that the lake is home to a giant serpent.
The scientific explanation for the changing colors of Tsomgo Lake is that the lake is very shallow and the water is very clear. This means that the light from the sky and the surrounding mountains is able to penetrate the water and reflect off of the bottom of the lake. The different colors that are seen in the lake are caused by the different wavelengths of light that are reflected. For example, blue light has a shorter wavelength than red light, so it is able to penetrate the water more deeply and reflect off of the bottom of the lake. This is why the lake often appears blue or green.
The changing colors of Tsomgo Lake are a beautiful sight to behold and are one of the reasons why the lake is such a popular tourist destination. The lake is also a popular spot for fishing and boating.