Kidney beans is the poorest source of protein among the given options. So option "C" is the correct option in regards to the given question.Kidney bean is nothing special but a variety of commonly found beans. The name is given based on the shape of the bean. People confuse the red kidney beans with other types of beans due to its color. Raw kidney beans are more toxic than any other variety of beans as it contains a very high proportion of phytohemagglutinin.