Had to look for the missing details of this question and here is my answer.
The main purpose of President Obama here in this section of this speech is to let the Americans be inspired in doing a collective work towards a better future and also for the future of the country as citizens of the United States. The answer for this would be the third option.
Answer:
Bicycles can influence the level of pollution positively due to no usage of gas, which exudes carbon dioxide into the atmosphere and contributes to the greenhouse effect. If more people rode bicycles everyday as opposed to public transportation or personal vehicles, pollution levels would fall significantly.
It is a, because he is bald and ashamed of it.