Asource of variation that is inherent in a system and predictable is typically known as:

The right answer is common error.

A common error (or random error) is when, from one measure to another, the value obtained may be overvalued or underestimated in relation to the real value.

An example of a random error is the measurement of time with a timer. The error comes from the reaction time of the experimenter at start-up and at the end of the timer. Since this reaction time is not always the same, the measured value can be overestimated or underestimated. It is understandable that a repetition of the measures can alleviate the random error.

the offspring would all be white. if the parents are both white flowers then they have the genotype rr, which when crossed results in an all white punnet square.