Some touch receptors sense a difference in pain or what?
Options:
- (A) heat
- (B) cold
- (C) skin
- (D) nerves
- (E) color
- (F) contact
- (G) smell
- (H) motion
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Let's think first: Some touch receptors sense differences in temperature or pain. Heat and temperature are the same. Some touch receptors sense differences in heat or pain.... So the answer is [(A)]


What does the organ of the eye sense?
Options:
- (A) Gluons
- (B) Photons
- (C) Neutrons
- (D) Energy
- (E) heat
- (F) distance
- (G) sunlight
- (H) Sound waves
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Let's think first: Sight is the ability to sense light, and the eye is the organ that senses light. Light is made of photons . The eye is an organ that can sense photons.... So the answer is [(B)]


Flowing water from a mountain can dissolve carbon in what kind of rock?
Options:
- (A) magma
- (B) loose soil
- (C) loose dirt
- (D) precipitation
- (E) pumice
- (F) limestone
- (G) wind and rain
- (H) andesite
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Let's think first: Flowing water can slowly dissolve carbon in sedimentary rock. Limestone is a type of sedimentary rock. Flowing water can slowly dissolve carbon in limestone.... So the answer is [(F)]