7. What’s the answer to this question

Here is your answer
B) [tex]x=5[/tex]
REASON:
Given,
[tex] {3}^{x}=243 [/tex]
[tex] {3}^{x}=3×3×3×3×3 [/tex]
[tex] {3}^{x}={3}^{5} [/tex]
Since, base is same so exponential power will be same
Hence,
[tex] x=5 [/tex]
HOPE IT IS USEFUL