Which two statements correctly describe an extended service set (ESS)?

According to the Lecture 3 - Radio Frequency and Antenna Fundamentals - Part 2 document2, an extended service set (ESS) is a group of basic service sets (BSSs) that share a common SSID and are connected by a distribution system (DS). Each BSS within the ESS has its own unique BSSID, which is the MAC address of the AP.