Which are true about Python?

A. Class and instance variables can be accessed either by custom-designed functions or by direct reference.

B. Both class and instance variables are preceded by self when referenced after construction inside the class definition.

C. Every class definition must be written with an __init__() method in order for the definition to run without an error.

D. Every class definition must be written with an __init__() method in order to instantiate objects in that class without error.