English Grammar – Spot the error (choose the erroneous segment or ‘‘No error’’). Sentence: The principals of equal justice for all is one of the cornerstones of our democratic way of life.

Introduction / Context:
This classic error-spotting item checks two common issues: confusing “principals” with “principles,” and number agreement between the grammatical subject and the verb. English exams frequently combine a diction error with a subtle agreement trap to test precise usage.

Given Data / Assumptions:

• Target meaning is “principles” (fundamental beliefs), not “principals” (heads of schools or main participants).
• The clause reads: “The principals of equal justice … is one of the cornerstones …”.
• The intended idea is about a foundational ideal in a democracy.

Concept / Approach:
“Principle” = rule/ideal; “principal” = head/primary. Use “principle(s)” for ethics and justice. For agreement, either make the head noun singular (“The principle … is …”) or plural with a matching verb (“The principles … are …”). The test focuses on the wrong word choice in segment A; choosing the correct word also clarifies agreement.

Step-by-Step Solution:

Verification / Alternative check:
Substitute synonyms: “foundational idea of equal justice.” That supports “principle,” not “principal.” Agreement then follows naturally.

Why Other Options Are Wrong:

• B: Phrase is acceptable once the subject is correctly set to singular “principle”.
• C and D: Idiomatic and grammatically fine.
• E: Not valid because an error exists in A.

Common Pitfalls:
Mistaking “principal/principle”; overlooking that the head noun controls the verb form, not the nearest noun.

Final Answer:
The principals of equal justice