Correct Answer: 5, 3, 1, 2, 4

Solution : Given:
1. Sinister 2. Sinuous 3. Sinhalese 4. Sinusitis 5. Sinecure

Step 1: Compare the first, second, and third letter of each word. Since all the words have the same letter S , i , and n , then move on to the next letter.
Step 2: The fourth letter of each word is e , h , i or u . Based on the alphabetical order of these letters, we can arrange them – Sin e cure, Sin h alese, Sin i ster, Sin u ous, Sin u sitis.
Step 3: Compare the fifth letter of (Sinu o us, Sinu s itis). Sinu o us will come before Sinu s itis in the sequence as o comes before s in the alphabetical system.

So, the sequence is Sinecure, Sinhalese, Sinister, Sinuous, Sinusitis, or 5, 3, 1, 2, 4. Hence, the fourth option is correct.