Answer:
a.The rental of any ski equipment you need
b.The cost of a lift ticket
d,The wages you forgo by going skiing
Explanation:
True cost is the monetary cost of doing something. In addition it includes the cost of foregoing an alternative action.
Rental of ski equipment and cost of lift ticket are the monetary costs incurred when you go skiing with your friend.
The opportunity cost is the alternative foregone in order to go skiing, that is the wages you are not earning while you are skiing.
Opportunity cost is considered by individuals and businesses in making the best choice between alternatives.