Q: Where do leeches live in relation to their hosts?
Options:
- (A) In their beds
- (B) body water
- (C) competing for resources
- (D) In their shoes
- (E) loose soil
- (F) In their intestines
- (G) important habitats
- (H) On their surface
A: So, my chain of thought: Some parasites live on the surface of their host. Leeches are external parasites. Leeches live on the surface of their hosts. The answer is (H).

Q: What increases the stability of ecosystems?
Options:
- (A) overpopulation
- (B) water consumption
- (C) loose soil
- (D) Quality of life
- (E) agriculture
- (F) deforestation
- (G) ecotourism
- (H) trees
A: So, my chain of thought: Biodiversity increases the productivity and stability of ecosystems. Ecotourism, on the other hand, can help to conserve biodiversity. Ecotourism increases the stability of ecosystems. The answer is (G).

Q: What have humans collected and grown as food for thousands of years?
Options:
- (A) sunlight
- (B) fungi
- (C) plants
- (D) rocks
- (E) fungus
- (F) salmon
- (G) ferns
- (H) poison
A:
So, my chain of thought: Humans have collected and grown mushrooms for food for thousands of years. Mushrooms are also fungi. Humans have collected and grown fungi for food for thousands of years. The answer is (B).