Answer:
To point out the mental and physical difficulties faced by the military team.
Explanation:
The killing of Osama Bin Laden was one of the most important parts of history especially for the American people after the attack on the World Trade Center. The September 11 attacks became the remembering point of what the world-renowned terrorist group, the Al-Qaeda did to the United States.
And in his speech, the then-president Barack Obama uses the metaphor "borne the heaviest share of the burden" in describing the role of the military team that took out the terrorist leader. His use of this metaphor suggests the heavy toil and stress the whole nation has been put under by the attack and how it had left everyone shaken to the core. And it was this group of military people who were tasked with 'executing' the act of avenging and carrying the burden of the whole nation.
Thus, the correct answer is the first option.