I'll give if you can guess what is 5+10

5+10= 15.

Explanation:

5+10=15.

"Beginning 10 years ago, the Soviets challenged the Western alliance with a grave new threat, hundreds of new and more deadly SS-20 nuclear missiles capable of striking every capital in Europe."

In this selection, Reagan call communism "a grave new threat". He compares it to nuclear missiles to show how severe the damage could be. The other options do not work because they do not speak of anything as being a threat. They talk about how the city has been rebuilt, how protesters should continue their work for change, and that things are well in the Western world.