Answer:
D. It teaches readers about an interesting Chinese custom and causes them to determine that the minister is trying to be polite.
Step-by-step explanation:
From the excerpt, Option D is the correct answer that shows purpose and effect.
It's clear that the passage reveals an interesting Chinese custom which truly astonished the guests. The purpose of this passage is to teach readers about this interesting Chinese custom; which every reader will be surprised to know. Also, the effect of the excerpt causes readers to know that the minister was actually being polite by mustering a quiet burp.
Therefore, option D is the correct answer.