5. Given that $\left\{a_{n}\right\}$ is a geometric sequence, and $a_{n}>0, a_{2} a_{4}+2 a_{3} a_{5}+a_{4} a_{6}=2025$, then the value of $a_{3}+a_{5}$ is ( ).
A. 15
B. 25
C. 35
D. 45
5. From $2025=a_{2} a_{4}+2 a_{3} a_{5}+a_{4} a_{6}=a_{3}^{2}+2 a_{3} a_{5}+a_{5}^{2}=\left(a_{3}+a_{5}\right)^{2}$, we know that the correct choice is D.