In spreadsheet applications like Microsoft Excel, the shortcut key to insert the current system date into a cell is:
\[
Ctrl + ;
\]
This shortcut quickly captures the date from your system clock and places it into the selected cell without requiring manual entry.
Explanation of Other Options:
(B) Ctrl + T: Used to create a table from selected data.
(C) Ctrl + D: Fills down content from the cell above.
(D) Ctrl + '1: Invalid shortcut (possibly a typo).
Hence, the correct answer is option (A).