Answer:
C. Playgrounds are rival in consumption, and the optimal number of playgrounds is three.
Explanation:
The computation is shown below:
For 3 playgrounds, total willingness to pay is
= 200 + 1600 + 800
= 2600 > Marginal cost (2250).
And,
For 4 playgrounds, total willingness to pay is
= 100 + 1400 + 700
= 2200 < Marginal cost (2250).
Therefore, 3 playgrounds should be considered as an optimal and playground would be rival