Exercise 7: Given: Sale(customer, store, product, price) and the constraints: A customer buys from only one store. There is a unique price for each product in a store, but the same product can have a different price in different stores. a) What are the FDs implied by the above description? b) What are the candidate keys? c) Explain why Sale is not in 3NF. d) Decompose Sale into 3NF. e) Is the decomposition dependency preserving? Why