- Time decay
- Data-driven
- Position-based
- Linear
The correct answer is: Linear
Linear attribution model distributes the credit for the conversion equally across all clicks on the path. In the Linear attribution model, each touchpoint in the conversion path—in this case the Paid Search, Social Network, Email, and Direct channels—would share equal credit (25% each) for the sale.
Read more here: https://support.google.com/analytics/answer/1662518