Through checks and balances
<span>Andachtsbilder. Andachtsbilder is a german word used in English in art history to describe Christian devotional images designed as aids for prayers or contemplations of the emotional sufferings during Jesus' life. It has a strong emphasis on the grief and sufferings of Jesus Christ and the figures close to him. By the mid-15th century Andachtsbilder had influenced large monumental works, and were becoming increasingly popular.</span>
The answer is D because answers A, B, and C are simply spreading American culture throughout America, thats not cultural diffusion by any means.
Extraneous
An <em>extraneous variable</em> is a variable in an experiment that you are not intentionally studying. These variables usually provide undesired affects on the experiment.
In this example, the independent variable is whether a sentence is humorous or not, and the dependent variable is the memory performance score. However, because the humorous sentences are only given to males, and the non-humorous sentences are only given to females, gender becomes an extraneous variable as you are not intentionally testing gender's relation to the dependent variable, but it is still affecting the experiment.
