Christine, a seven-year-old girl, is upset because her parents are getting divorced. she has begun to wet the bed again, and she insists upon carrying her old security blanket. christine is using the defense mechanism of

I believe the answer is: Regression

Regression refers to the process of slipping to our earlier stage of development when facing difficult situation rather than making an adaptation to face it.

This coping mechanism would make the person who do it act in non-suitable manner considering their age. Other example would be college students who throw temper tantrum like children when facing things that they considered as offensive.

"Nullification Crisis of 1832 centered around Southern protests against the series of protective tariffs (taxes) that had been introduced to tax all foreign goods in order to boost the sales of US products and protect manufacturers in the North from cheap British goods. The South, being predominantly agricultural, and reliant on the North and foreign countries for manufactured goods, saw the protective tariffs as severely damaging to their economy. During the administration of John Quincy Adams his Vice President, John C. Calhoun, had drafted the South Carolina Exposition, a document that declared the tariffs were unconstitutional that caused the Nullification Crisis bringing the sectional interests of the North and the South into open conflict for the first time."