If \( b_n = \int_{0}^{\pi/2} \frac{\cos^2(nx)}{\sin x} \, dx , \, n \in \mathbb{N} , \) then
\( b_3 - b_2 , \, b_4 - b_3 , \, b_5 - b_4 \) are in an A.P. with common difference \( -2 \)
\( \frac{1}{\,b_3 - b_2\,} , \, \frac{1}{\,b_4 - b_3\,} , \, \frac{1}{\,b_5 - b_4\,} \) are in an A.P. with common difference \( 2 \)
\( b_3 - b_2 , \, b_4 - b_3 , \, b_5 - b_4 \) are in a G.P.
\( \frac{1}{\,b_3 - b_2\,} , \, \frac{1}{\,b_4 - b_3\,} , \, \frac{1}{\,b_5 - b_4\,} \) are in an A.P. with common difference \( -2 \)