Using Poisson Approximation :
Here, $\lambda =\binom{4}{3}* \frac{1}{7*7}$
So, ${\mathbb{P}}$$($at least 3 of them are born on the same day of the week$)$ $\approx 1-e^{-\lambda} = 1-e^{\binom{4}{3}* \frac{1}{7*7}} = 0.0787$ which is close to option $(d)\; 0.072$. Other Options : $(a) = 0.007 , (b) =0.019, (c) = 0.043, (e) = 0.122$