Assume That Black Beans and Rice Are Staples in the Diet

Assume that black beans and rice are staples in the diet of one particular family.How would you know if these goods are substitutes?  

A)  If the price of black beans rises and the consumption of rice remains the same, they would be substitutes. 
B)  If the price of black beans rises and the consumption of rice increases, they would be substitutes. 
C)  If the price of black beans rises and the consumption of rice decreases, they would be substitutes. 
D)  If the price of black beans rises and the consumption of both goods remains the same, they would be substitutes.