In the 19th century, found that difference thresholds reflect ratios rather than absolute amounts.

The answer to this question is Ernst Weber
This finding was correlated to how intense is a person' reaction when receiving a certain stimulus. According to his finding, when a person receive two fold stimulus from the previous one, that person will not necessarily display two fold intensity because of the thresold.

The answer is D. Immigrants and aliens would need to carry documentation at all times

Explanation: Arizona Senate Bill 1070 "Support Our Law Enforcement and Safe Neighborhood Act" is a legislative Act signed into law by Arizona Governor, Jan Brewer on 23rd of April, 2010.

The law requires law enforcement officials to enforce existing federal immigration laws in the state by checking the immigration status of a person they have "reasonable suspicion" of being an illegal immigrant in the U.S; violation of the law is a state misdemeanor. The U.S federal law on immigration requires alien above the age of 18 to have their proper identification at all times. It is a federal misdemeanor when an alien is found wanting.

The law was meant to take effect as from June 29, 2010, but a preliminary injunction was issued to block the law as a result of legal challenges over its constitutionality and compliance with civil rights law.

It was gutted during a U.S Supreme Court ruling in 2012 and a settlement with plaintiff in 2016.