Which two statements are correct regarding Spring Boot 2.x Actuator Metrics? (Choose two.)

Which two statements are correct regarding Spring Boot 2.x Actuator Metrics? (Choose two.)
A . An external monitoring system must be used with Actuator.
B . The metrics endpoint /actuator/metrics is exposed over HTTP by default.
C . Timer measures both the number of timed events and the total time of all events timed.
D . Custom metrics can be measured using Meter primitives such as Counter, Gauge, Timer, and Distribution Summary.
E . A metric must be created with one or more tags.

Answer: A,B