Answer
$1.66\times10^{-17}m$.
Work Step by Step
$\lambda=\frac{h}{p}=\frac{h}{mv}$
$\lambda=\frac{6.626\times10^{-34}J \cdot s}{(1.00\times10^{-14}kg)(0.004\;m/s)}= 1.66\times10^{-17}m $
This wavelength is unimaginably tiny, and the blood cell will not exhibit detectable wavelike properties.