The question says
[tex]\text{irrational number}\times rational\text{ number = irrational number}[/tex]
Therefore the best option is
[tex]\begin{gathered} \text{irrational number = }\sqrt[]{3} \\ \text{ratioanl number=}\sqrt[]{49} \\ Therefore, \\ \sqrt[]{3}\times\sqrt[]{49}=\sqrt[]{3}\times7=7\sqrt[]{3} \\ 7\sqrt[]{3}\text{ is irrational} \end{gathered}[/tex]
The answer is C.
