Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 34 to 40.

In recent years, immigration has become a hot-button issue in the United States. With the rise of anti-immigrant sentiment and the election of Donald Trump as president, the debate over immigration policy has reached new heights. However, what does the data actually show about immigration in the U.S.?

Contrary to popular belief, the number of undocumented immigrants living in the U.S. has been on the decline since 2007. According to a report by the Pew Research Centre, there were an estimated 10.7 million unauthorised immigrants in the U.S. in 2016, down from a peak of 12.2 million in 2007. This decline can be attributed to a number of factors, including increased border enforcement and a decrease in the number of people coming from Mexico.

Another misconception is that immigrants are a drain on the U.S. economy. In reality, immigrants contribute significantly to the economy through their labour and consumption. According to a study by the National Academies of Sciences, Engineering, and Medicine, immigrants added $ 2 trillion to the U.S. gross domestic product (GDP) in 2016. Furthermore, immigrants are more likely to start their own businesses than native-born Americans, creating jobs and stimulating economic growth.

One of the most contentious issues surrounding immigration is the question of whether immigrants commit more crimes than native-born Americans. However, numerous studies have shown that immigrants are actually less likely to engage in criminal activity than their native-born counterparts. According to a report by the Cato Institute, immigrants are about half as likely to be incarcerated as native-born Americans. Furthermore, cities with high levels of immigration tend to have lower crime rates than those with low levels of immigration.

While it is clear that immigration has many positive effects on the U.S., there are still legitimate concerns that need to be addressed. For example, some argue that immigrants put pressure on public services such as schools and hospitals. However, research has shown that the fiscal impact of immigration is generally positive, with immigrants paying more in taxes than they receive in benefits.

What does the word "which" in paragraph 2 refer to? A. minerals B. soy products C. omega-3 fatty acids D. fish