Q: Fact 1: Poison causes harm to living things. Fact 2: Carbon monoxide and cyanide are poisons. Given the two facts above, what causes harm to living things?

Options:
[a]. toxins;
[b]. vitamins;
[c]. bacteria;
[d]. cyanide;
[e]. leeches;
[f]. h2o;
[g]. oxygen;
[h]. Pesticides;
A:
[d].