What is meant by a "source of error"?

Sources of error are basically sources of uncertainty in your measurements. Every measurement, no matter how precise we believe it to be, contains some uncertainty simply because of how we measure it.

Sub to pewdiepie he must stay #1

Ican answer some, but not all! 2.) sensory info not being transmitted to the brian will result in a lack of responses that could be life saving. 4.) sensory adaption will helo people recognize certain images or objects that will give them a clearer understanding and expand their knowledge. them also become familiar with their surroundings. 8.) light the retina detect an object as it passes through the pupil and into the retina. 12.) cones in the retina us see color. they us see red. blue and green