A consumer will buy a new product rather than an existing product

A) when the MU/P of the new product is less than the MU/P of the existing product.
B) when the substitution of the new product for the old product increases the consumer's total utility.
C) only if the new product has a lower price than the existing product.
D) only if the MU of the new product exceeds the MU of the existing product.