What is the primary lesson behind the "United Breaks Guitars" case?$$

Question $9$ options:

a$)$

$$Social media is only effective for customer complaints.

b$)$

$$Online video has the power to reach millions of people at a very low cost.

c$)$

$$A well$-$executed PR strategy can help control negative social media messages.

d$)$

$$Customer service should not be outsourced.

e$)$

$$Companies must be active in monitoring their brands online in order to respond in a timely manner to customer issues.