Which of the following systems is/are causal? y(t) = x(1-t) y(t) = x(1-1) + x(t-1) y(t)=x(lt-2) t-2 y(t) = X(t)- cos(w(t+1)) dt -Itl y(t) = x(T-1) y(t) = x(1)-u(t) y(t)=x(t-1)-u(t+1) y(t) = x(2t)-u(t) Which of the following systems is/are causal? y(t) = x(1-t) y(t) = x(1-1) + x(t-1) y(t)=x(lt-2) t-2 y(t) = X(t)- cos(w(t+1)) dt -Itl y(t) = x(T-1) y(t) = x(1)-u(t) y(t)=x(t-1)-u(t+1) y(t) = x(2t)-u(t)