In the following question, a sentence is divided into numbered parts. Identify the part that contains an error in tense consistency. Sentence: “When one stops being optimistic, believes that he is worthless, and stops hoping for a better future, it is only then that the moment of actual failure happened.”

Introduction / Context:
This question tests the correct use of verb tenses in a complex sentence about optimism and failure. The sentence uses present tense forms in the first part and then unexpectedly shifts to past tense in the final clause. The candidate must determine which part contains the tense inconsistency that disrupts the logical time frame of the sentence.

Given Data / Assumptions:

• The sentence is: “When one stops being optimistic, believes that he is worthless, and stops hoping for a better future, it is only then that the moment of actual failure happened.”
• Part (1) likely contains “When one stops being optimistic, believes that he is worthless.”
• Part (2) likely contains “and stops hoping for a better future, it is only then that.”
• Part (3) contains “the moment of actual failure happened.”
• The earlier verbs “stops,” “believes,” and “is” are in the simple present tense.

Concept / Approach:
The concept here is tense consistency within a sentence. If a sentence describes a general truth or a habitual situation, it should maintain present tense throughout. The use of “happened” at the end suggests a particular event in the past and clashes with the general present tense framework. The correct form should be “the moment of actual failure happens,” not “happened.”

Step-by-Step Solution:

Verification / Alternative check:
Rewrite the sentence correctly: “When one stops being optimistic, believes that he is worthless, and stops hoping for a better future, it is only then that the moment of actual failure happens.” Now all verbs are in the present tense, and the sentence clearly expresses a timeless general statement about failure. Since the correction applies only to part (3), our choice is verified.

Why Other Options Are Wrong:

• Part (1): The series of present tense verbs “stops being optimistic, believes that he is worthless” is consistent and grammatically correct.
• Part (2): The phrase “and stops hoping for a better future, it is only then that” also uses correct present tense forms.
• “No error”: This is not correct because the tense shift to “happened” is improper in a sentence that otherwise operates in the present tense.

Common Pitfalls:
Examinees sometimes accept tense shifts unconsciously if the meaning remains roughly understandable. Others may focus on the emotional content of the sentence and overlook the technical grammar. It is important to scan all verbs carefully and check whether the time reference is consistent, especially in sentences that express universal truths or habitual patterns of behaviour.

Final Answer:
Part (3) is the correct answer, since “the moment of actual failure happened” should be corrected to “the moment of actual failure happens” to maintain tense consistency.