Answer
The log is made out of Oak.
Work Step by Step
Using the formula $Density=\frac{Mass}{Volume}$ and the conversion factors shown in the formula, the density can be calculated in g/cm^3.
$Density = \frac{19.8 lb}{2.7 gal}\times\frac{453.592 grams}{1 lb}\times\frac{1 gal}{3785.41 cm^{3}} = 0.8787 \frac{g}{cm^{3}}$. Therefore the log is made out of oak since the density of the log (0.8787 g/cm^3) nearly matches the density of the oak (0.9 g/cm^3)
