Sometimes it is not feasible to conduct causal research because meeting all of the conditions (for example a probability sample when you aren't sure how many people are in the population). In these cases researchers may conduct research which is almost as good.

Quasi-experimental.

Explanation:

Quasi-experimental research maintains the manipulation of an independent variable without the subjects were randomly assigned to conditions. Nonequivalent group designs, pre-test and post-test, and interrupted time-series designs are among the important types. Quasi-experimental research removes the challenge of directionality since it requires manipulating the independent variable.

yes, since there is a positive and a negetive if the positive and negitive wasn't there wouldn't a flow electricity in it.

the first question's answer is a.