What is the ratio of displacement thickness to boundary layer thickness for a linear distribution of velocity \(\frac{u}{{{u_\infty }}} = \frac{y}{\delta }\) in the boundary layer on a flat plate, where δ is the boundary layer thickness and u∞ is the free stream velocity?

• A. 0.5
• B. 0.67
• C. 0.75
• D. 0.8