In an experiment on the effects of massed versus distributed practice on learning, introductory psychology students who volunteered for extra credit were randomly assigned to one of two groups. Both groups were to practice a perceptual-motor task five times for 10 minutes each. Group 1 did all five 10-minute practice sessions in one evening while group 2 was asked to do one 10-minute practice session a night for five consecutive nights. All of the participants in Group 1 completed the experiment, but only 30% of the participants in Group 2 showed up for all five nights. This study is an example of confounding by .

The correct answer is attrition

Explanation: Attrition occurs when participants leave during a study.

Longitudinal research is a study that provides an understanding of changes  behavior over time. For these studies, it is necessary to  develop a panel of households that will be monitored and researched throughout  of time.

the answer is "meiosis ii in the mother".

the procedure of meiosis includes two divisions of the hereditary material. the main division is known as the decrease division – or meiosis i – on the grounds that it lessens the quantity of chromosomes from 46 chromosomes or 2n to 23 chromosomes or (n depicts a solitary chromosome set). in people, the decrease division results in two sperm cells each with 23 chromosomes or an egg cell with 23 chromosomes and one disposed of polar body. the second division – or meiosis ii – is called equational division. the two sperm cells split again creating four sperm cells, each with 23 or n chromosomes. in oogenesis, the egg cell and polar body partition to shape the ovum and two extra polar bodies. along these lines, the posterity are guaranteed to get one portion of the chromosomes from the mother and one half from the dad.

answer; regard the action of other people negatively;