which of the following is a complex number?

Answer:
C.[tex]3 \sqrt{ \frac{7}{5} } + \sqrt{ - \frac{9}{5} } [/tex]
Step-by-step explanation:
Recall that:
[tex] \sqrt{ - 1} = i[/tex]
For this particular question, you just have to look for the radical containing a negative sign under the square root i.e a negative radicand.
That will be option C.
This is given as
[tex]3 \sqrt{ \frac{7}{5} } + \sqrt{ - \frac{9}{5} } [/tex]
This can be rewritten to reveal the complex part as:
[tex]3 \sqrt{ \frac{7}{5} } + \sqrt{ \frac{9}{5} }i [/tex]
Therefore the correct answer us option C