Biosphere reserves differ from national parks and wildlife sanctuaries in

The correct option is B People are integral part

• An ecosystem with plants and animals of unusual scientific and natural interest is known as a biosphere reserve. UNESCO has given this label for protecting these sites.
• A park in use for conservation purposes is known as a National park. It is basically a reserve of natural, semi-natural, or developed land that a sovereign state declares or owns.
• A naturally occurring sanctuary, such as an island, which protects species from getting hunted, predated or poached is called as a wildlife refuge. It is also known as a wildlife sanctuary.
• Limited or no human activity is permitted in national parks and sanctuaries whereas, in Biosphere reserves, people play an integral part.

So, the correct answer is 'People are an integral part'.