In a heat exchanger with steam outside the tubes, a liquid gets heated to $45$C$,$ when its flow velocity in the tubes is $2$ m$/$s$.$ If the flow velocity is reduced to $1$ m$/$s$,$ other things remaining the same, the temperature of the exit liquid will be

Less than $45$C

More than $45$C

Equal to $45$C

Initially decreases and remains constant thereafter