If f(t) is the step-response of a linear time invariant system, then its impulse response h(t) is given by:(where ‘t’ indicates continuous time domain)

• A. \(h\left( t \right) = \smallint f\left( t \right)\)
• B. \(h\left( t \right) = \frac{d}{{dt}}f\left( t \right)\)
• C. \(h\left( t \right) = {\left[ {f\left( t \right)} \right]^2}\)
• D. h(t) = f(t)