$\text {A large dirigible measures \(18 \mathrm {~m}\) in diameter and is \(100 \mathrm {~m}\) long. The thin boundary layer can}$

$\text {A large dirigible measures \(18 \mathrm {~m}\) in diameter and is \(100 \mathrm {~m}\) long. The thin boundary layer can}$ $\text {be assumed to be developing on a flat plate with thickness at the leading edge. The drag}$ $\text {contributed by the shear stress due to the boundary layer for a dirigible speed of \(10 \mathrm {~m} / \mathrm { s }\) is}$$\text { approximately:}$

A) $\delta = 3.6 \sqrt { v x / U _ { \infty } }$
B) $\delta = 3.3 \sqrt { \nu x / U _ { \infty } }$
C) $\delta = 3 \sqrt { v x / U _ { \infty } }$
D) $\delta = 2.8 \sqrt { v x / U _ { \infty } }$