Why are there three mouths in a Starbucks straw? (equivalent to three small ones merged into one big one)

That straw is very thin. In order to slow down the flow rate and increase the relative volume of the surface area (the smaller the radius, the larger the circumference: area value), it can increase heat dissipation.

However, the thin straw is very tired to suck, and it is very uncomfortable to drink only a little at a time, so I made three tubes and drank a little more. ...