JEE Advanced 2020 Full Test 4 Paper 2

Two blocks A and B, each of mass m are connected by means of a pulley-spring system on a smooth inclined plane of inclination θ as shown in the figure. All the pulleys and spring are ideal. Now, B is slightly displaced from its equilibrium position. It starts to oscillate. Time period of oscillation of B will be (Take m=4kg,K=5N∕m, π=3.14)