When an evolutionary biologist designs an experiment to test a hypothesis, which term is used to describe the variable that the scientist changes among his/her groups of study organisms.

Explanation:

Controlled experiment=An experiment in which only one variable is changed

Independent variable=The variable that is deliberately changed in an experiment

Dependent variable=The variable this is observed and changes in response to the independent variable

common management practices in dairy and poultry farming are: (i) proper shelter facilities and their regular cleaning. (ii) some basic hygienic conditions such as clean water, nutritious food, etc. (iii) animals are kept in spacious, airy, and ventilated place.