Bro if u dont know this answer you better pay attention in class cause this is the easiest thing i have ever seen. And if you cant find the answer in your class book come back in here and i will hook you up.<span />
Answer:
3 - Photoreceptors.
Explanation:
Photoreceptors are a sensor that is connected to your retina. They sense light and send the message to your brain. The sensors automatically squint your eyes if something will blind you.
The correct answer is 'photoreceptors'.
When oxygen is absent, anaerobic respiration occurs ('an' means without).
That is true, species can breed within