Concept:
- A Reason explains an Assertion when it fills in the step between the stated cause and the stated result.
- Laying the two sentences out as a sequence shows at once whether that step is present.
Step 1: Write the Assertion as cause and result.
Cause: political accommodation of ethnicity failed. Result: civil war. The sentence jumps straight from one to the other, leaving a gap in the middle.
Step 2: See whether the Reason fills that gap.
The Reason says distrust between the Sinhala and Tamil communities turned into widespread conflict. That is precisely the missing middle, how a policy failure became a war.
Step 3: Check the sequence against what happened.
Sinhala was made the sole official language in 1956, Sinhala applicants were favoured for government jobs and university places, and the constitution gave Buddhism a protected position. Tamils saw their language, culture and rights being set aside, distrust grew, and by the 1980s militant groups were demanding an independent Tamil Eelam.
Cause, distrust and war follow one another exactly as the two statements describe.
Step 4: Rule out the other options.
Neither statement is false, so options (C) and (D) fail. The Reason is not a separate unrelated fact but the very link in the chain, so option (B) fails as well.
Final Answer: (A) Both (A) and (R) are correct and (R) is the correct explanation of (A).