To reflect a point across the y-axis, we simply change the sign of the x-coordinate while keeping the y-coordinate the same.
The original endpoints are (1,1) and (4,4).
When we reflect (1,1), the x-coordinate changes from 1 to -1 while the y-coordinate remains the same. Therefore, the reflected endpoint is (-1,1).
Similarly, when we reflect (4,4), the x-coordinate changes from 4 to -4 while the y-coordinate remains the same. Therefore, the reflected endpoint is (-4,4).
So, the correct answer is (-1,1) and (-4,4).