Four, a certain project, if contracted by Team A and Team B, can be completed in $2 \frac{2}{5}$ days, with a payment of 1800 yuan; if contracted by Team B and Team C, it can be completed in $3 \frac{3}{4}$ days, with a payment of 1500 yuan; if contracted by Team C and Team A, it can be completed in $2 \frac{6}{7}$ days, with a payment of 1600 yuan. Under the condition of ensuring the project is completed within one week, which team should be chosen to contract the project alone to minimize the cost?
Four, Solution List as follows:

From the table above, "on the premise of completing this work within a week," it is clear that choosing Team B would incur the least cost.