Final answer:
C) Immigration policy and border security
Immigration policy and border security are significant issues in presidential elections, highlighted in the 2016 election cycle with President Trump's call for a border wall and differing attitudes towards Syrian refugees. Debates around immigration are tied to broader societal issues, including national identity. Presidential efforts to tackle major issues like healthcare reform are often complicated by political polarization.
Step-by-step explanation:
The important issue in the current presidential election you mentioned is Immigration policy and border security. Immigration reform and securing the borders have been pivotal topics in U.S. policy debates. The emphasis on immigration rose particularly during the 2016 election cycle when candidates like President Donald Trump highlighted the need for a wall along the Southern border to reinforce border security.
Additionally, there were differing stances on the admission of Syrian refugees into the country. As the U.S. diversifies, immigration remains a contentious issue linked to broader societal debates, including national identity and civil rights.
President Barack Obama's tenure saw a range of issues being tackled, among them, attempting to fulfill his promise of comprehensive healthcare reform, aiding in economic recovery post-the financial crisis, and addressing climate change. However, presidential efforts are often challenged by political polarization, which has intensified since the 2008 election, making the enactment of significant policies an arduous task.