The Circle or Ellipse Shown in the Calculator-Generated Graph Was $y_{1}$

Multiple Choice

The circle or ellipse shown in the calculator-generated graph was created using function mode with a square viewing window. What are the two functions $y_{1}$ and $y_{2}$ that were used to obtain the graph whose equation is given?
- $(x-1) ^{2}+(y-1) ^{2}=1$

A) $y_{1}=-1+\sqrt{1-(x-1) ^{2}}, y_{2} =-1-\sqrt{1-(x-1) ^{2}}$

B) $y_{1}=-1+\sqrt{1-(x-1) ^{2}}, y_{2}=1-\sqrt{1-(x-1) ^{2}}$

C) $\mathrm{y}_{1}=1+\sqrt{1-(\mathrm{x}-1) ^{2}}, \mathrm{y}_{2}=1-\sqrt{1-(\mathrm{x}-1) ^{2}}$

D) $y_{1}=1+\sqrt{1-(x-1) ^{2}}, y_{2}=-1-\sqrt{1-(x-1) ^{2}}$