Which of the following factors correctly explain$($s$)$ the importance of social media for marketers?

Customers acquired through word$-$of$-$mouth avenues are worth twice as much as are those attracted through other channels.

According to Intuit co$-$founder Scott Cook, "A brand is no longer what we tell the consumer it is$-$it is what consumers tell each other it is$."$

Social interactions contribute to the retention of existing customers.

All of these factors correctly explain the importance of social media for marketers.

McKinsey and Company estimates that between $20\%$ and $50\%$ of all purchases are driven primarily by word$-$of$-$mouth recommendations.