Refrigeration and Freezing

For a spherical food product of diameter $a$, Plank's geometric shape factors $P$ and $R$ are:

Options:

• (A) $P = 1/6$ and $R = 1/24$
• (B) $P = 1/2$ and $R = 1/8$
• (C) $P = 1/4$ and $R = 1/16$
• (D) $P = 1$ and $R = 1$