Answer:
a. Produce 3 units of output in the short run and exit in the long run
Step-by-step explanation:
According to the question, the data provided is as follows
The market price is $4
Based on the above information, since the price on the market is 4
So we can conclude that the firm could produced the 3 units of output and after that it would be exit in the long run
Therefore the correct option is a
And all the other options are wrong