To determine how many bottles the store owner needs to sell to earn at least $400 in profit, we can use the following formula:
Profit = Profit per bottle × Number of bottles
In this case, the profit per bottle is $2, and the target profit is at least $400.
Let \( x \) be the number of bottles sold. We can set up the inequality:
\[ 2x \geq 400 \]
Now, divide both sides by 2:
\[ x \geq 200 \]
This means the store owner needs to sell at least 200 bottles to earn a profit of at least $400.
So the correct response is:
at least 200 bottles.