Intergate : $\int \large\frac{5}{7}$$\sqrt {\cos (7x)}. \sin 7x dx$

Question

$(a)\;(\tan 7x)^{3/2}+c \qquad(b)\;(\cot 7x)^{3/2}+c \qquad(c)\;\frac{-10}{147} [(\cos 7x)^{3/2}]+c\qquad (d)\;(\sin 7x )^{3/2} +c$