Some Meghalayan folk songs preserve:

Historical narratives and tribal myths
Recipes and farming techniques
Scientific discoveries
Fashion trends

The correct answer is: a) Historical narratives and tribal myths.

Meghalayan folk songs are a rich source of information about the history and culture of the state. They often tell stories of the past, including the migration of different tribes to the region, battles fought, and important events. They also preserve tribal myths and legends, which help to explain the world around people.

Recipes and farming techniques are not typically found in Meghalayan folk songs. These types of information are more likely to be passed down through oral tradition or in written form. Scientific discoveries are also not typically found in Meghalayan folk songs. This is because the state has a long history of oral tradition, and scientific knowledge was not widely disseminated until relatively recently. Fashion trends are also not typically found in Meghalayan folk songs. This is because the state has a relatively conservative culture, and fashion is not as important as it is in some other parts of the world.

In conclusion, the correct answer is: a) Historical narratives and tribal myths.