Answer:
a) New cars and used cars (Substitutes)
b) Houses and Washing Machines (Complements)
c) UGG boots and Kindle e-readers (Unrelated)
d) iPads and Kindle e-readers (Substitutes)
Step-by-step explanation:
New cars and used cars are substitutes because a consumer who does not have enough money to buy a new car, can easily buy a used car and one can choose to buy a new car over a used car and yet utility will not be changed.
Houses and washing machines are complements because you need a washing machine in a house to help you wash and you also need a house for you to have a place to keep the washing machine. Hence both can be used simultaneously to achieve utility maximization.
UGG boots and Kindle e-readers are unrelated since they cannot be used at the same time to maximize utility, neither can one be used as a substitute for another.
iPads and Kindle e-readers are considered substitute because you can either choose to use an iPad to read a book or you can use Kindle e-readers to do the same. Hence, a consumer can choose one over the other and still achieve same utility.