In a $\Delta$le ABC $a:b:c=4:5:6$.The ratio of the radius of the circle to that of the incircle is

Question

$(a)\;\large\frac{15}{4}$$\qquad(b)\;\large\frac{11}{5}$$\qquad(c)\;\large\frac{16}{7}$$\qquad(d)\;\large\frac{16}{3}$