Final answer:
Aluminum (Al) has the greatest atomic radius among the elements P, S, Al, Si, and B, because atomic radius increases down a group and decreases across a period.
Step-by-step explanation:
To determine which element among P (phosphorus), S (sulfur), Al (aluminum), Si (silicon), and B (boron) has the greatest atomic radius, we must refer to their positions on the periodic table. Atomic radius generally increases as we move down a group and decreases as we move across a period from left to right.
Therefore, by comparing the positions of the given elements, we can determine that Al (aluminum) has the largest atomic radius since it is located further to the left and lower in the periodic table than the other elements listed.