Neurons that detect light stimuli are
a) photoreceptors
b) olfactory receptors
c) chemoreceptors
d) mechanoreceptors

The correct answer is option A, Photoreceptors

Explanation:

Photoreceptors basically function by changing their color when exposed to light. In human body photoreceptors are  found in the eyes. When light strike on the photoreceptors, electrical signals are generated which are sent to the brain through the optic nerves. Human eye has two types of photoreceptors- Rods and Cones. Rods detect light sensation while cones detect the color.  

i believe the answer is c

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.