Why did President Reagan call for Soviet leader Gorbachev to “tear down” the Berlin Wall?

Why did President Reagan call for Soviet leader Gorbachev to “tear down” the Berlin Wall?
a. He believed that Germany could remain divided without the wall.
b. He believed that the wall was a threat to US national security.
c. He believed that the wall’s removal would signal a new era of freedom.
d. He believed that the wall’s removal would improve relations with the Soviet Union.