$.$ Consider a data set that has $35\%$ missing values for one of the categorical descriptive features. The data

set has $40000$ instances. Which of the following approaches should be followed with reference to this

descriptive feature if a classication tree is induced on this data set? Simply write down the letter$($s$)$ of

the correct approach$($es$)$: $(2)$

$($a$)$ Remove the descriptive feature

$($b$)$ Impute the missing values using the mean or median over the available values

$($c$)$ Impute the missing values using the mode over all the available values

$($d$)$ Apply complete case analysis, and remove all of the instances with missing values for this feature

$($e$)$ Nothing needs to be done with these missing values