The angle between the straight lines $\frac{x+4}{2}=\frac{y+5}{5}=\frac{z+6}{3}$ and $\frac{x-4}{10}=\frac{y-5}{2}=\frac{z-6}{-10}$ is

90°

The correct answer is Option (2) → 90°

$\vec{v_1}||l_1=2\hat i+5\hat j+3\hat k$

$\vec{v_2}||l_2=10\hat i+2\hat j-10\hat k$

so $\vec{v_1}.\vec{v_2}=20+10-30=0$

$\vec{v_1}⊥\vec{v_2}$ ⇒ angle is 90°