Answer : Option B

Explanation :

This problem is similar to the problems we saw in compound interest.
We can use the formulas of compound interest here as well.
$MF#%\text{Rate of increase = }\dfrac{1}{5} \times 100 = 20\%\\\\ \text{Height after 2 years = }\text{P}\left(1 + \dfrac{\text{R}}{100}\right)^\text{T} = 50\left(1 + \dfrac{20}{100}\right)^2 \\\\ = 50\left(1 + \dfrac{1}{5}\right)^2 = 50\left(\dfrac{6}{5}\right)^2 = \dfrac{50 \times 6\times 6}{5\times 5} = 2 \times 6 \times 6 = 72\text{ cm}$MF#%