Answer:
The sentence which contains a fallacy is:
B. Unless everyone in the U.S. including our grandparents can successfully use social media, we will be left behind.
Explanation:
A fallacy takes place when our logic is flawed, which undermines the strength of our argument. We have an example of a fallacy in letter B. Let's analyze why.
According to sentence B, we only have two options:
1. Have everyone successfully use social media;
2. Be left behind.
The writer of the sentence makes it seem that these are the only two ways to go. We either do A, or we'll get B. However, that is not true. There are several other ways to go. Even if our parents do not learn to successfully access social media, we can still stay ahead. Therefore, we can safely say that letter B has a fallacy.