Hey there!
Here is your answer:
The proper answer to this question is option C "5.2".
Reason:
First put the numbers from least to greatest:
2,3,5,7,9
The mean would be the middle number of the set.
Which would be 5.2!
Therefore the answer is option C
If you need anymore help feel free to ask me!
Hope this helps!
~Nonportrit