In Order to Conclude That Cells Are Part of an Engram

In order to conclude that cells are part of an engram, which condition(s) must be satisfied? (Select all that apply.)

A) The cells must be active both at the time of the learning experience and at the time of the memory test.
B) Their presence must be correlated with the generation of the appropriate memory.
C) When directly activated they can produce the behavioral expression of the memory.
D) When inhibited or deleted, the behavioral expression of the memory will be prevented or reduced.
E) None of the above