Hello!
First you have to count from point C to x = 1
C is 3 points from the line
This means the reflection is 3 points from the line the other way
Count 3 spaces after x = 1
C is now at (3, -7)
Now you count up till you reach y = -3
C is 4 points away from y = -3
You go 4 points above y = -3
Now C is at (4, 1)
The answer is D(4, 1)
Hope this helps!