Spot the grammatical error in the sentence. Select the part (A–D) that contains an error; if the sentence is correct as written, choose ‘‘No error.’’ Sentence: The success of our efforts depend upon the number of people who actually use the new methods.

Introduction / Context:
This is a subject–verb agreement question. We must decide whether the finite verb agrees in number with its subject and whether any other phrase creates an error.

Given Data / Assumptions:

• Subject phrase: ‘‘The success of our efforts’’ (singular head noun ‘‘success’’).
• Verb phrase given: ‘‘depend upon’’ (plural form).
• Prepositional phrase: ‘‘of our efforts’’ does not change subject number.

Concept / Approach:
The finite verb must agree with the head of the subject noun phrase. Intervening prepositional phrases and relative clauses do not change number. Therefore, a singular subject requires a singular verb.

Step-by-Step Solution:
Identify the head noun: head = ‘‘success’’ (singular).Check the verb: supplied verb = ‘‘depend’’ (plural).Correct form: ‘‘depends’’ (singular) to agree with ‘‘success’’.Recast: ‘‘The success of our efforts depends upon the number of people who actually use the new methods.’’

Verification / Alternative check:
If we invert the sentence to test agreement: ‘‘Success depends…’’ sounds correct; ‘‘Success depend…’’ sounds wrong—confirming the error.

Why Other Options Are Wrong:

• A: Noun phrase is fine.
• C: Relative clause ‘‘who actually use…’’ correctly refers to plural ‘‘people’’.
• D: Phrase is idiomatic.

Common Pitfalls:
Allowing the plural object of the preposition (‘‘efforts’’) to mislead the verb choice.

Final Answer:
depend upon the