If $a^2,b^2,c^2\;$ are in AP ,$\frac{1}{b+c},\frac{1}{a+c},\frac{1}{b+a}\;$ are in

Question

$(a)\;AP\qquad(b)\;HP\qquad(C)\;GP\qquad(d)\;None\;of\;the\;above$