Convert the direct speech sentence "I said, my grandfather snored throughout the night" into indirect speech and select the most appropriate reported form.

Introduction / Context:
This question checks your understanding of reported speech, sometimes called indirect speech, in English grammar. When we move from direct speech, which quotes the exact words of the speaker, to indirect speech, we often need to change tenses, pronouns, and sometimes time expressions. Here the reporting verb "said" is in the past, and the original reported clause describes an action that took place before the act of speaking. The correct answer must show proper backshifting of tense and maintain the meaning that the grandfather snored for the entire night.

Given Data / Assumptions:

Direct speech sentence: I said, "My grandfather snored throughout the night."
Reporting verb "said" is in the past tense.
The action of snoring happened during one whole night before the act of reporting.
We must convert this into an indirect speech sentence starting with "I said that...".
The meaning about duration, "throughout the night", must be preserved.

Concept / Approach:
When converting from direct to indirect speech with a past reporting verb, we usually move the tense of the reported clause one step back in time. Simple present becomes simple past, and simple past becomes past perfect. In the original sentence, "snored" is simple past, so the correct indirect form should normally use past perfect: "had snored". The conjunction "that" is usually added after "said" when introducing the reported clause, especially in formal or exam English. We also need to decide whether a continuous aspect is required. Since the sentence presents snoring as a completed action covering a time period (the night), the simple past perfect is more suitable than past perfect continuous.

Step-by-Step Solution:
Step 1: Identify the reporting verb and its tense: "said" is simple past. Step 2: Identify the reported clause: "My grandfather snored throughout the night." Step 3: Recognise that "snored" is simple past referring to an action completed before the moment of saying. Step 4: Apply backshift: simple past in direct speech usually becomes past perfect in indirect speech, so "snored" becomes "had snored". Step 5: Insert the conjunction "that" after "said" to form a natural reported clause: "I said that my grandfather had snored throughout the night." Step 6: Compare this sentence with the given options and select the one that matches exactly.

Verification / Alternative check:
Check each option carefully. Option B keeps the verb in simple past, "snored", which is sometimes used in casual speech but does not follow strict exam rules of backshifting. Option A omits the conjunction "that", which is grammatically possible but less formal. Exam questions normally prefer the fuller structure with "that". Option D uses "had been snoring", which is a past perfect continuous construction and places too much emphasis on the ongoing process rather than a completed whole night action. The most accurate and formally correct structure, especially for exam standards, is "I said that my grandfather had snored throughout the night", which is option C.

Why Other Options Are Wrong:
Option A lacks the conjunction "that", which makes it slightly less formal than standard exam preference, although the tense is correct.
Option B uses simple past "snored" without backshift, which does not reflect the typical rule for reported speech with a past reporting verb in exam grammar.
Option D uses past perfect continuous and suggests focusing on the process of snoring rather than the completed fact that the grandfather snored throughout the night, which is not necessary here.

Common Pitfalls:
Many learners forget to backshift the tense when the reporting verb is in the past, especially if the original sentence already uses simple past. Another common error is to overuse continuous forms like "had been snoring" even when a simple perfect form is enough. Finally, candidates sometimes ignore the small but important word "that". While conversational English may drop it, written exam English generally keeps it. Remember to apply the backshift rule consistently unless the situation clearly demands an exception, such as universal truths.

Final Answer:
I said that my grandfather had snored throughout the night.