Q: Fact 1: Changes in the pH of soil can cause plants to die. Fact 2: Sulfur lowers pH in soil. Given the two facts above, what can cause plants to die?

OPTIONS:
[I] Planting flowers.
[II] Winter.
[III] Pollution.
[IV] Condensation.
[V] Photosynthesis.
[VI] Sulfur.
[VII] coal.
[VIII] bacteria.
The answer is:
[VI]