Answer: OPTION D
Step-by-step explanation: In simple words, competitive parity products refers to those products which are necessary for an organisation to have in their operations so they can effective compete with other participants in the market.
In the given case, Bill was having problem regarding selling Yachts as he did not have any space, Thus, due to lack of one product he was having difficulty in operating the business of some other product.
Hence yachts and docks are an example of competitive parity products.