Exercise 1: Price vs. Opportunity Cost — Possible Solution
================================================================

The price of a choice is simply the direct monetary amount you pay
for it - a concrete, visible number on a receipt or invoice. Opportunity
cost is a broader, real concept: the value of the single best
alternative you gave up by making that choice, which may include far
more than money alone, or may not match the price at all.

A clean example where the two genuinely differ: attending a free
university lecture. The PRICE is literally zero - you pay nothing to
walk in and sit down. But the real OPPORTUNITY COST is not zero at
all: it's whatever else you could have done with that same block of
time - working a paid shift, studying for a different class, or
simply resting. If you could have earned 15 pounds working during that
same hour, the real opportunity cost of attending the "free" lecture
is that foregone 15 pounds, even though the lecture's own price tag
was nothing.

This shows price and opportunity cost are measuring genuinely
different things: price captures only the direct monetary transaction,
while opportunity cost captures the real, full value of what you
actually gave up - which can be zero when the price is high, or high
when the price is zero, or anything in between.

ANSWER: Price is the direct monetary amount paid for a choice, while
opportunity cost is the real value of the next-best alternative given
up - the two can differ substantially, as with a free lecture that has
a price of zero but a real opportunity cost equal to whatever paid
work or other activity you could have done with that same time instead.

WHY THIS WORKS AS AN ANSWER
------------------------------
This gives a concrete example where the price (zero) and the real
opportunity cost (nonzero) genuinely diverge, making the conceptual
distinction tangible rather than purely abstract.