Answer:
The suffering and the emotional cost of the Holocaust must be remembered.
Explanation:
In the given passage from Ronald Reagan's "Speech to Holocaust Survivors", he expressed the importance of remembering the <em>"immeasurable pain of the Holocaust"</em>. He stressed that <em>"its significance is not lost on this generation or any future generation".</em>
Despite the event long gone in the past, <em>"now a dry scar"</em> on the minds and memories of people, it must not be forgotten. He also expresses his belief that <em>"[acting as] the vessel of remembrance"</em> of the Holocaust victims would be a <em>"reunion"</em> of the past and the present, the dead and the living.
Thus, the correct answer is the first option.