The angle between the lines given by $x^2-y^2=0$ is

The correct option is D

$90°$

Find the angle between the lines.

Consider the given Equation as,

$$\begin{gathered} \Rightarrow x^2-y^2=0 \\ \Rightarrow \left(x+y\right)\left(x-y\right)=0 \\ \therefore x+y=0,x-y=0 \end{gathered}$$

Slope of $x+y=0$ is $m_1=-1$

Slope of $x-y=0$ is $m_2=1$

Product of the slope is $m_1\times m_2=-1\times 1=-1$

Since the product is $-1$, so the angle between the lines is equal to $90°$

Hence, the correct answer is Option D.