Answer:
d. To engage the reader with a current event
Step-by-step explanation:
The writer begins with Obama's reinstallation of solar panels which is a more recent event so as to engage the reader with a current event. This introduction tells the reader that there is something happening presently. Subsequent references emphasize that this current event has its root in prior times.
The prior times in this case stands for President Jimmy Carter who first did what Obama was doing presently and President Ronald Reagan who did not have the foresight to do the same thing.