Explanation
- A
Only one
Only one. All three country–resource pairs are keyed.
- B
Only two
Only two. Under-counts.
- C
All the three
All the three. Botswana–diamond, Chile and the third pair are all correctly matched.
- D
None
None. All three hold.
Summary. Official Set A key is (c) all three. Botswana is diamond-rich; Chile is copper-lithium country; the third pair is also a standard resource match. All three are correct.