Light is reflected from a plane mirror as illustrated. Which row is always right?
- Asymbol of angle $X$: $i$; relationship between $X$ and $Y$: $X = Y$
- Bsymbol of angle $X$: $i$; relationship between $X$ and $Y$: $X + Y = 90^{\circ}$
- Csymbol of angle $X$: $r$; relationship between $X$ and $Y$: $X = Y$
- Dsymbol of angle $X$: $r$; relationship between $X$ and $Y$: $X + Y = 90^{\circ}$