The input x(t) and output y(t) of a system are related as\(y(t) = \int\limits_{ - \infty }^t {x\left( t \right)} \cos \left( {4t} \right)dt\)The system is

• A. time - invariant and stable
• B. stable and not time - invariant
• C. time - invariant and not stable
• D. not time - invariant and not stable