300 millimeters=30 centimeters
I think there are no potential bias since expect for when the test subjects were selected. There is no mention of how the subjects were selected. This could result to lurking variables which are is the hereditary susceptibility to tumors and congenital conditions of the mice that might be in the form of tumors already present in the mice's bodies.
ANSWER
![3 {x}^{2} y \sqrt[4]{y}](https://tex.z-dn.net/?f=3%20%7Bx%7D%5E%7B2%7D%20y%20%5Csqrt%5B4%5D%7By%7D%20)
EXPLANATION
We want to simplify:
![\sqrt[4]{81 {x}^{8} {y}^{5} }](https://tex.z-dn.net/?f=%20%5Csqrt%5B4%5D%7B81%20%7Bx%7D%5E%7B8%7D%20%7By%7D%5E%7B5%7D%20%20%7D%20)
We can split the radical sign to obtain:
![\sqrt[4]{81} \times \sqrt[4]{ {x}^{8} } \times \sqrt[4]{ {y}^{5} }](https://tex.z-dn.net/?f=%20%5Csqrt%5B4%5D%7B81%7D%20%20%5Ctimes%20%20%5Csqrt%5B4%5D%7B%20%7Bx%7D%5E%7B8%7D%20%7D%20%20%5Ctimes%20%20%5Csqrt%5B4%5D%7B%20%7By%7D%5E%7B5%7D%20%7D%20)
Or
![\sqrt[4]{81} \times \sqrt[4]{ {x}^{8} } \times \sqrt[4]{ {y}^{4} \times y}](https://tex.z-dn.net/?f=%20%5Csqrt%5B4%5D%7B81%7D%20%20%5Ctimes%20%20%5Csqrt%5B4%5D%7B%20%7Bx%7D%5E%7B8%7D%20%7D%20%20%5Ctimes%20%20%5Csqrt%5B4%5D%7B%20%7By%7D%5E%7B4%7D%20%20%5Ctimes%20y%7D%20)
![\sqrt[4]{81} \times \sqrt[4]{ {x}^{8} } \times \sqrt[4]{ {y}^{4}} \times \sqrt[4]{y}](https://tex.z-dn.net/?f=%20%5Csqrt%5B4%5D%7B81%7D%20%20%5Ctimes%20%20%5Csqrt%5B4%5D%7B%20%7Bx%7D%5E%7B8%7D%20%7D%20%20%5Ctimes%20%20%5Csqrt%5B4%5D%7B%20%7By%7D%5E%7B4%7D%7D%20%20%5Ctimes%20%20%5Csqrt%5B4%5D%7By%7D%20)
![\sqrt[4]{ {3}^{4} } \times \sqrt[4]{ {x}^{8} } \times \sqrt[4]{ {y}^{4}} \times \sqrt[4]{y}](https://tex.z-dn.net/?f=%5Csqrt%5B4%5D%7B%20%7B3%7D%5E%7B4%7D%20%7D%20%20%5Ctimes%20%20%5Csqrt%5B4%5D%7B%20%7Bx%7D%5E%7B8%7D%20%7D%20%20%5Ctimes%20%20%5Csqrt%5B4%5D%7B%20%7By%7D%5E%7B4%7D%7D%20%20%5Ctimes%20%20%5Csqrt%5B4%5D%7By%7D%20)
Recall that:
![\sqrt[n]{ {a}^{m} } = {a}^{ \frac{m}{n} }](https://tex.z-dn.net/?f=%20%5Csqrt%5Bn%5D%7B%20%7Ba%7D%5E%7Bm%7D%20%7D%20%20%3D%20%20%7Ba%7D%5E%7B%20%5Cfrac%7Bm%7D%7Bn%7D%20%7D%20%20)
![{3}^{4 \times \frac{1}{4} } \times {x}^{8 \times \frac{1}{4} } \times {y}^{4 \times \frac{1}{4} }\times \sqrt[4]{y}](https://tex.z-dn.net/?f=%7B3%7D%5E%7B4%20%5Ctimes%20%20%5Cfrac%7B1%7D%7B4%7D%20%7D%20%20%5Ctimes%20%20%7Bx%7D%5E%7B8%20%5Ctimes%20%20%5Cfrac%7B1%7D%7B4%7D%20%20%7D%20%20%5Ctimes%20%20%7By%7D%5E%7B4%20%5Ctimes%20%20%5Cfrac%7B1%7D%7B4%7D%20%7D%5Ctimes%20%20%5Csqrt%5B4%5D%7By%7D%20)
![3 {x}^{2} y \sqrt[4]{y}](https://tex.z-dn.net/?f=3%20%7Bx%7D%5E%7B2%7D%20y%20%5Csqrt%5B4%5D%7By%7D%20)
i think the answer is b:a hope thats it