Answer: Quintile.

**Explanation:** - **Option A (Decile):** Incorrect. The second decile includes observations above the 10th percentile and at or below the 20th percentile. The 19th observation in a sample of 75 does not fall into this range. - **Option B (Quintile):** Correct. The 19th observation is located at the 25th percentile, calculated as follows: $$\text{Percentile} = \frac{(1 + n)}{100} \times \text{observation} = \frac{(1 + 75)}{100} \times 19 = 25.0$$ The second quintile includes observations above the 20th percentile and at or below the 40th percentile, which aligns with the 25th percentile. - **Option C (Quartile):** Incorrect. The second quartile includes observations above the 25th percentile and at or below the 50th percentile. Since the 19th observation is exactly at the 25th percentile, it falls into the first quartile, not the second.

Author: LeetQuiz Editorial Team