In which of the following, handpicking method is useful for separation of substances.

Handpicking is a method for removing slightly larger impurities that can be picked up by hand. The main idea is that the impurities should be larger than or equal to the size of the main component, making identification and selection easier. As a result, because it is easier to identify and pick stones from rice, only stones can be removed from rice using the handpicking method.