Q: You are presented with the quiz "what kind of circulatory system do reptiles have?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "chordates have a complete digestive system and a closed circulatory system" and "because reptiles are vertebrates, they are chordates". So, what's the best answer to the question?

OPTIONS:
- open
- systemic
- complex
- dense
- cold
- three
- closed
- organ

A: closed

Q: You are presented with the quiz "a what can have a negative impact on ecosystem" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "cutting down trees has a negative impact on an ecosystem" and "trees are cut down in the forest and are then sent to a paper mill". So, what's the best answer to the question?

OPTIONS:
- paper mill
- A virus
- deforestation
- storm
- disease
- rainfall
- tree
- Pollution

A: paper mill

Q: You are presented with the quiz "Why do male gametes swim from male to female reproductive organs?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "sperm had to swim from male to female reproductive organs for fertilization" and "male gametes are called sperm". So, what's the best answer to the question?

OPTIONS:
- temperature changes
- to leave the egg
- fertilization
- competition
- it needs them
- to feed
- permineralization
- to heal themselves

A: fertilization

Q: You are presented with the quiz "Some animals communicate through what?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "sound can be used for communication by animals" and "snarls and barks are the sounds they make". So, what's the best answer to the question?

OPTIONS:
- chemical reaction
- eating quietly
- vibrating quickly
- being silent
- chemical changes
- hormones
- barks and snarls
- chemical messengers

A:
barks and snarls