Extraneous variables are threats to the ________ of a study

How does the poverty rate in the United States compare to other Western democracies?

a. The poverty rate in the United States is roughly the same. b. The poverty rate in the United States is substantially higher. c. The poverty rate for non-white Caucasians in the United States is much higher. d. The poverty rate for single-parent families in the United States is much lower.

Which of the following is defined as "a plan of a study that organizes observations in such a way as to establish a sound logical basis for causal inference"?

a.) exploratory research b.) operationalization c.) a hypothesis d.) research design