An unit impulse function in continuous form is defined to be

• A. δ(t) = t
• B. δ(t) = 1
• C. \(\delta \left( t \right) = \left\{ {\begin{array}{*{20}{c}}{\infty ,\;\;t = 0}\\{0,\;\;t \ne 0}\end{array}} \right.\)
• D. \(\delta \left( t \right) = \left\{ {\begin{array}{*{20}{c}}{0,\;\;t = 0}\\{1,\;\;t \ne 0}\end{array}} \right.\)