Answer: B
Correct answer: Ctrl + Down Arrow
Ctrl + Down Arrow jumps to the last filled cell of the contiguous block below the cursor, and stops at the edge of any gap. From an empty cell it jumps to the next filled one, or to the bottom of the sheet if there is none. The same works in all four directions, and adding Shift selects everything passed over - so Ctrl + Shift + Down selects a whole column of data in one keystroke, which is the fastest way to select a long range. Ctrl + End, the fourth option, is different: it goes to the last used cell of the whole sheet, the intersection of the last used row and column. That is often further out than the visible data, because Excel remembers cells that once held content - and that stale boundary is what inflates file sizes and can be reset by deleting the surplus rows and columns and saving. Alt + Down opens a drop-down list in the cell.