Final answer:
The largest atomic radius is represented by F.
Step-by-step explanation:
The atomic radius is the measure of the size of an atom. It is defined as half the distance between the nuclei of two atoms that are bonded together.
The atomic radius generally decreases from left to right across a period and increases from top to bottom within a group in the periodic table.
Among the options given (a. Cl, b. F, c. F-, d. Cl-), F has the largest atomic radius because it is located at the top left corner of its group in the periodic table and is the farthest from the nucleus.