The buyer–seller relationship has changed dramatically in the past 20 years. This is PRIMARILY because:

Sellers now have more technology to help them find buyers.
Social media has made it easier for buyers and sellers to connect with each other.
The internet has shifted the power in the buying process from the seller to the buyer.
Buyers have so many distractions that they need more frequent contact to help them through the buying process.

The correct answer is:

The internet has shifted the power in the buying process from the seller to the buyer.