$\begin {array} {1 1} (a)\;Increases\: in\: proportion\: to\: T \\ (b)\;Decreases\: in\: proportion\: to\: \large\frac{1}{T} \\ (c)\;Increases\: in\: proportion\: to\: T^2 \\ (d)\;Decreases\: in\: proportion\: to\: \large\frac{1}{T^2} \end {array}$