Something is wrong with one of these singular-plural sets. Identify it:

Correct option is C

Option (c) is the incorrect pair in the context of standard modern English usage.

Explanation:

Many English words borrowed from Latin retain their original Latin plural forms. Let us examine each pair:

·       Option A: Minimum – Minima

This is correct.

"Minimum" is singular and "Minima" is its correct Latin plural form.

Example: The teacher asked students to list the minima required for admission.

·       Option B: Stimulus – Stimuli

This is correct.

"Stimulus" is singular and "Stimuli" is its proper plural form, especially in scientific and psychological contexts.

Example: The doctor studied how different stimuli affect the nervous system.

·       Option C: Symposium – Symposia

This is problematic.

"Symposium" is a word that originally comes from Greek and later Latin. While "Symposia" is a correct classical plural, in modern English usage, especially in general contexts, the preferred and more widely accepted plural is "Symposiums". Therefore, using "Symposia" may sound archaic or overly formal today.

Correct modern usage: Symposium – Symposiums.

·       Option D: Radius – Radii

This is correct.

"Radius" is singular, and "Radii" is the correct Latin plural used especially in mathematics and geometry.

Example: The radii of the two circles are equal.

·       Conclusion: While "Symposia" is not grammatically wrong, it is not the commonly accepted plural in modern English. Hence, option (c) is considered incorrect or unsuitable in regular usage. The others are correct both grammatically and in standard usage.