Meaning of 'all about'

[marian]

Test No. incompl/elem-18 "Making an Appointment", question 2

To start with, can you ......... what session 2 was all about?

(a) retain
(b) remain
(c) remind
(d) remember

Test No. incompl/elem-18 "Making an Appointment", answer 2

To start with, can you remember what session 2 was all about?

Correct answer: (d) remember
_________________________

can you explain me more clear the expresion "was
all about?

[Torsten]

This means can you remember the topic of session 2?

TOEIC listening, photographs: The lone climber

[Kale]

hi Torsten,
could you explain me the difference among recall, remind & remember