To determine which of the given options is a rational number that lies between \(\sqrt{7}\) and \(\sqrt{8}\), we first need to evaluate the approximate values of \(\sqrt{7}\) and \(\sqrt{8}\):
- \(\sqrt{7} \approx 2.64575\)
- \(\sqrt{8} \approx 2.82843\)
Now, we can check each of the options:
- \(56\): This is much larger than \(\sqrt{8}\).
- \(\frac{5}{6}\): This is approximately \(0.8333\), which is less than \(\sqrt{7}\).
- \(\frac{19}{7}\): This is approximately \(2.7142857\), which falls between \(\sqrt{7}\) and \(\sqrt{8}\).
- \(\frac{3}{4}\): This is \(0.75\), which is also less than \(\sqrt{7}\).
- \(63\): This is much larger than \(\sqrt{8}\).
From the evaluations, the only rational number that lies between \(\sqrt{7}\) and \(\sqrt{8}\) is \(\frac{19}{7}\).