Correct Answer: CBAD

Solution : The first option is correct.

• The first sentence states that Aksenov swore for something, and that is (C): Aksenov swore that he had not killed the merchant.
• The second sentence clarifies more with reason, and that is (B): He had not seen the merchant after they had tea together.
• The third sentence states that he swore for one more thing, and that is (A): He swore that the eight thousand roubles that he had were his own money.
• Now we are left with the fourth sentence, obviously, that is (D) - But his voice was broken, and he trembled with fear as though he were guilty.

Therefore, the correct answer is CBAD.