The correct answer is: Both 1 and 4.
A particular price level, there are no forces tending to move it either up or down, it means that the firm is in equilibrium and the price is in equilibrium.
The firm is in equilibrium when the quantity supplied is equal to the quantity demanded. This means that the firm is producing the amount of output that consumers are willing and able to buy at the current price.
The price is in equilibrium when there is no tendency for it to change. This means that the price is at a level where the quantity supplied is equal to the quantity demanded.
In conclusion, both the firm and the price are in equilibrium when there are no forces tending to move them either up or down.