The correct option is A 4 dollars
The price is increased from 5 dollars to 9 dollars.
To represent addition on the number line, we have to move the desired number of units to the right.
So, we move one unit at a time to the right of 5 until we reach 9 on the number line.
The total number of jumps on the number line is the increase in price.
Hence, the increase in price is 4 dollars.