Which of following statements is incorrect for a first order reaction, where $T_x$ is the time taken for the reactant to drop by that % number.

Question

$\begin{array}{1 1}(a)\;T_{99.9\%}=10T_{50\%}\\(b)\;T_{75\%}=2T_{50\%}\\(c)\;T_{99.9\%}=25T_{25\%}\\(d)\;T_{50\%}=5\normalsize T_{25\%}\end{array}$