单项选择题

Questions 18 to 20 are based on the following passage. At the end of the passage, you will be given 15 seconds to answer the questions. Now listen to the passage. What does the speaker imply was the purpose of Lincoln’s speech

A.To suggest changes to government structure.
B.To criticize the practice of slavery.
C.To convince the South to surrender.
D.To inspire Northerners to support the war.