What was the significance of the immigration acts of 1921 and 1924? :
a they limited immigration from mexico for the first time.
b they created a category of "special immigrants," which included relatives of u. s. citizens living abroad.
c they made immigration requirements qualitative, rather than quantitative.
d they set quotas on immigration from certain areas of europe, asia, and africa.
e they based annual quotas on a flat one-sixth of one percent of the national population in 1920.

The answer is D they set quotas on immigration from certain areas of Europe, Asia, and Africa. This introduced a quota system to limit to the number of people entering the United States.  Some of the reasons why this was implemented was due to the economic hardships of the Great Depression.

for starters, there is the structural trend of rising primary government expenditure as a share of gdp, which reached 36% in 2014, up from 22% in 1991. this increase reflected a political desire to address the poverty and inequality that had gone unaddressed during previous decades. to support the increase, brazil’s government increased taxes on consumption and promoted progress toward labor-market formalization. nonetheless, public investment, particularly in infrastructure, took a hit. in fact, with the exception of the 2005-2008 period, total investment as a share of gdp has remained below 20% since 1991.

answer: this is because archeologists keep finding artefacts and ancient ruins dated more than 10000 to 15000 years, date around scientists said humans discovered language; which is at least mysterious as scientists always have said that is necessary to have a language to have architecture and some basic maths.

explanation: brainlest