$\frac{1}{4}:\frac{1}{2}:\frac{1}{4}$ ratio of TT, Tt, tt can be depicted mathematically binomial expression as $= (ax + by)^{2}$. Monohybrid cross can be denoted as 1 : 2 : 1 (genetic) and the expression of binomial is also 1 : 2 : 1 so monohybrid cross can be represented in any of the given option (a or b or c) because their results are same