Functions sum() and cumsum() produce the same result.

The fillna() can also fill individual missing values for different columns.

Assertion. A quantile refers to equally distributed portion of a data set.

Reason. A median divides a distribution in 2 quantiles while a quartile divides a distribution in 4 quantiles.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Assertion. Data aggregation produces a summary statistics of a dataset.

Reason. Data aggregation summarizes data using statistical aggregation functions.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.