= Solution
{c}
The <Reynolds number> compares <convective acceleration> with viscous <acceleration> in the <Navier-Stokes equation>:
$$
\mathrm{Re}=\frac{UL}{\nu}=\frac{\rho UL}{\mu}.
$$
At large <Reynolds number>, <inertia> dominates in the bulk; <viscous boundary layers> can still control wall <shear stress>, separation and <drag>. <Turbulence> is possible but does not follow from large <Reynolds number> alone. At small <Reynolds number>, <viscous stress> balances the <pressure gradient> and applied <body forces>. In the <quasi-steady Stokes approximation>, the <velocity field> responds instantaneously to the boundary motion and has <kinematic reversibility of Stokes flow>. Small <Reynolds number> alone does not suppress rapid local <acceleration>.
For a swimmer, take a characteristic <length> $L\sim1\,\mathrm m$ and <speed> $U\sim1\,\mathrm{m\,s^{-1}}$. The supplied <kinematic viscosity> gives
$$
\boxed{\mathrm{Re}\sim\frac{1\times1}{10^{-6}}=10^6\gg1.}
$$
Human swimming is therefore an <inertia>-dominated <fluid flow>, rather than <Stokes flow>.
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