The correct answer is: True.
Explanation
A standard golf ball has diameter about $42.67\text{ mm}$ (radius $r\approx2.1335\text{ cm}$). Its volume is
$V=\frac{4}{3}\pi r^3\approx\frac{4}{3}\pi(2.1335\text{ cm})^3\approx40.7\text{ cm}^3$.
A typical golf ball mass is about $45\text{ g}$, so its average density is
$\rho=\frac{m}{V}\approx\frac{45\text{ g}}{40.7\text{ cm}^3}\approx1.11\text{ g/cm}^3$.
Water has density $1.00\text{ g/cm}^3$, so a golf ball is denser than water and will sink. (Only specially made or unusually hollow/low-mass novelty balls would float.)