Correct Answer: -15

Solution : The correct option is -15 .

"Femto" is a metric prefix denoting 10 to the power of -15 . In scientific notation, it is used to represent one quadrillionth, or 0.000000000000001 . It's commonly employed in fields like physics and telecommunications to express small quantities, such as femtoseconds in time measurements or femtometres in length scales. Femtoseconds (fs), equivalent to 10 ^-15 seconds , are used in ultrafast laser studies to capture extremely brief processes, such as molecular reactions or electronic transitions, providing insights into the dynamics of microscopic events at an incredibly fast timescale.