What does 'to know the ropes' mean?

[Nenad11]

English Language Tests, Intermediate level

ESL/EFL Test #289 "English Slang Idioms (11)", question 7

"Once you know the ......... better, we will give you more responsibility," the boss said to the new trainee.

(a) lines
(b) slips
(c) straps
(d) ropes

English Language Tests, Intermediate level

ESL/EFL Test #289 "English Slang Idioms (11)", answer 7

"Once you know the ropes better, we will give you more responsibility," the boss said to the new trainee.

Correct answer: (d) ropes

Your answer was: incorrect
"Once you know the lines better, we will give you more responsibility," the boss said to the new trainee.
_________________________

Does the point of it go that once he get to know with the matter of his work better He will get more responsibility?

[Mister Micawber]

That is right.
_________________
Native English teacher at Mister Micawber's