To answer Part A, the question typically asks for the main message or intent of Reagan's speech. He is advocating for freedom and calling upon Soviet leader Gorbachev to take actions that would promote liberty and dismantle the barriers between East and West.
The excerpt that best supports this message is:
D. General Secretary Gorbachev, if you seek peace … Come here to this gate! Mr. Gorbachev, open this gate! (paragraph 3)
This excerpt directly calls upon Gorbachev to take decisive action towards freedom and peace, encapsulating Reagan's overall message of promoting liberation and the dismantling of oppressive barriers, specifically the Berlin Wall.