Q.In a Pandas DataFrame, which value for axis will be used to delete a column ? (A) axis = -1 (B) axis = 0 (C) axis = 1 (D) axis = 2

Understanding the axis parameter in Pandas

The axis parameter in Pandas tells operations which dimension of the DataFrame to work along. Think of a DataFrame as a two-dimensional table: it has rows stacked vertically and columns arranged horizontally.

Pandas borrowed NumPy's convention for labeling these dimensions:

• axis=0 runs down the rows (the vertical direction). Operations with axis=0 work across rows, meaning they affect or aggregate entire columns.
• axis=1 runs across the columns (the horizontal direction). Operations with axis=1 work along rows, meaning they affect or aggregate entire rows—or in the case of deletion, remove entire columns.

The naming can feel counterintuitive at first. When you specify axis=1 for deletion, you're saying "operate along the column axis," which means you're selecting columns to remove.

Deleting a column: the mechanics

When you call df.drop() to remove a column, you must specify axis=1:

df.drop('column_name', axis=1)

Without axis=1, Pandas defaults to axis=0 and tries to drop a row with that label, which will raise an error if no such row exists. …

The core idea here is understanding how Pandas interprets the axis parameter. In Pandas, axis=0 always refers to the index (rows), and axis=1 refers to the columns. The drop() method is designed to remove data along either axis, and the axis parameter is exactly what tells it which direction to work in. So the reason directly explains how the assertion works — it's not just a separate fact.

Let's walk through it step by step.

1. Check the Assertion: Does drop() delete both rows and columns?

   Yes. If you call df.drop('row_label') without specifying axis, it defaults to axis=0 and removes that row. If you call df.drop('col_name', axis=1), it removes that column. So the assertion is True.

2. Check the Reason: Does the axis parameter specify rows vs. columns?

   Yes. axis=0 means "operate along the index" — which translates to dropping rows. axis=1 means "operate along the columns" — dropping columns. So the reason is also True.

3. Is the reason the correct explanation? …