Livestock plays a crucial role in the livelihoods of:

Rural communities
Urban elites
Coastal fishermen
Industrial workers

The correct answer is: a) Rural communities.

Livestock plays a crucial role in the livelihoods of rural communities. It provides food, income, and employment for millions of people around the world. Livestock products, such as meat, milk, and eggs, are an important source of protein and other nutrients for people living in rural areas. Livestock also provides manure, which can be used to fertilize crops. In addition, livestock can be used to transport goods and people, and to provide draft power for plowing and other agricultural activities.

Option b) is incorrect because urban elites are not as reliant on livestock for their livelihoods as rural communities are. Option c) is incorrect because coastal fishermen are not as reliant on livestock for their livelihoods as rural communities are. Option d) is incorrect because industrial workers are not as reliant on livestock for their livelihoods as rural communities are.