Answer:
b. make fewer than 20 wedding cakes per month.
Explanation
Laura sells 20 wedding cakes per month.
Her monthly total revenue is $5,000.
Marginal Revenue = $5000 / 20 cakes = $250
The marginal cost of making a wedding cake is $300.
In order to maximize profits, Laura should make fewer than 20 wedding cakes per month.
The reason is that Laura's marginal cost is higher than her marginal revenue implying that she is spending more on each item than she is gaining.
By reducing one unit of output she will be gaining more revenue.
Profit Maximization Rule Definition states that if a firm chooses to maximize its profits, it must choose that level of output where Marginal Cost (MC) is equal to Marginal Revenue (MR) and the Marginal Cost curve is rising. i.e. it must produce at a level where MC = MR.
Hence Laura has to make fewer cakes