Displacement Thickness - GATE ME' 17 S1

The velocity profile inside the boundary layer for flow over a flat plate is given as u/U∞=sin⁡(πy/2δ), where U∞ is the free stream velocity and ′δ′ is the local boundary layer thickness. If δ∗ is the local displacement thickness, the value of δ∗/δ is A. 2π B. 1−2π C. 1+2π D. 0