A research does an evolution experiment to study the process

A research does an evolution experiment to study the process of adaptation. 12 different experiment populations are created, each by randomly selecting 100 males and 100 females from a single, large stock population. Six of these populations are then housed under environmental condition A, and 6 under environmental condition B. After 20 generations under these conditions, they measure traits in individuals from each of these populations. Variation in individual trait values is modelled as a function of population and environment. Is each factor fixed or random and are they crossed or nested?

Solution

Is each factor fixed or random and are they crossed or nested?

is factor random because we are using sample that is randomly selecting and they are crossed because there are different population