Answer:
option 3
Step-by-step explanation:
[tex]\frac{5- \sqrt{7} }{9-\sqrt{14} } = \frac{5- \sqrt{7} }{9-\sqrt{14} } \times \frac{9 + \sqrt{14} }{9 +\sqrt{14} }[/tex]
To rationalize the denominator choose the denominator and change the sign of the operation.