Select the option that expresses the given sentence in reported speech.
Mother said, “Abhinav slipped while trying to board a bus.”

The correct option is: "Mother said that Abhinav had slipped while trying to board a bus."

To convert the direct speech sentence into reported (indirect) speech, we follow these grammatical rules:
1. Reporting Verb: The reporting verb "said" remains "said" (or becomes "said that") when it is not followed by an object (unlike "said to me" which would change to "told me").
2. Conjunction: The conjunction "that" is used to introduce the reported speech, replacing the comma and quotation marks.
3. Tense Change: When the reporting verb is in the past tense ("said"), the tense of the verb inside the direct speech shifts back in time (backshift). Here, the verb in direct speech is in the Simple Past tense ("slipped"). According to rules of indirect speech, the Simple Past tense shifts to the Past Perfect tense ("had slipped"). The phrase "while trying to board a bus" remains unchanged as it describes the continuous action/state during which the slip occurred.
4. Pronouns/Nouns: The proper noun "Abhinav" remains unchanged.

Applying these transformations:
- Direct: Mother said, “Abhinav slipped while trying to board a bus.”
- Indirect: Mother said that Abhinav had slipped while trying to board a bus.