In the absence of an explicit formula, we can estimate the change in the option price due to a change in an input-such as o-by computing the following for a small value of : BSCall(S, K, 0 +6,1,1,8) - BSCall(S, K, 0 - , l', 1,8) 2 a. What is the logic behind this calculation? Why does need to be small? Vega In the absence of an explicit formula, we can estimate the change in the option price due to a change in an input-such as o-by computing the following for a small value of : BSCall(S, K, 0 +6,1,1,8) - BSCall(S, K, 0 - , l', 1,8) 2 a. What is the logic behind this calculation? Why does need to be small? Vega