You have to identify the opposite number of the number that is 4 units to the right of 1.
The first step is to determine which unit is 4 units to the right of 1, to do so there are two ways:
1) You can add the four units to 1:
2) You can count 4 units starting from 1 on the number line
The number we are looking for is 5.
Next is to identify its opposite number on the number line. The opposite number to 5 is on the same distance with respect to zero but to the left, i.e. it has the reverse sign.
The opposite number to 5 is -5
The correct option is A)-5