A、Underground in the mountain. B、On rock cliffs. C、In mountain spring. D、In mountain forest. C在对话中女士提到，在山间的小溪中能够发现金子。故答案为C)。

W: Is there a lot of oil and coal in your country?
M: (19) There is some,but my country is not among the leading producers. The oil and coal deposits are in the north of my country. Your country is a big oil producer,isn’t it?
W: Yes.it is. My country is famous for having those natural resources. We also have a lot of natural gas.
M: We have some too. Do you have a lot of coal?
W: No coal has been discovered in my country,but there may be undiscovered deposits. We don’t have many metal deposits.
M: There are a few in my country. We have deposit of gold,but they are very small.
W: When I traveled around your country,I bought some jewellery made of gold from your country. The jeweler told me that there are few gold mines in your country. (20) The gold was found in mountain streams.
M: That’s right. A few people go to find gold in rivers.
W: You have many trees in your country. That’s other natural resources.
M: It’s natural resources that we hardly use. Government policy is to conserve those forests.
W: I see. That’s probably a good idea. Too many forests are being destroyed.
M: Is your country’s environment being damaged by the oil industry?
W: (21) We have some inspections,but it is very hard to avoid pollution when extracting oil. There has been some damage,but it is under control.
19. What can we learn about the coal deposit in the man’s country?
20. Where are the gold mines in the man’s country?
21. What is the problem of oil industry in the woman’s country?