4. You're cleaning a data set with 1000 observations and notice that in 2 out of the 10 available columns you have missing data. The first column is categorical and has 50 missing data points, and the second column is continuous and has 100 missing data points. How should you handle this issue? Select the best answer. a. Delete all missing data b. Delete missing data for the categorical column, and impute for the continuous column c. Impute all missing data