Comma after "late": She's always late, isn't she?

[Donny]

English Grammar Tests, Elementary Level

ESL/EFL Test #35 "Question Tags (1)", question 8

She's always late .........

(a) is it?
(b) isn't she?
(c) isn't it?
(d) was she?

English Grammar Tests, Elementary Level

ESL/EFL Test #35 "Question Tags (1)", answer 8

She's always late isn't she?

Correct answer: (b) isn't she?
_________________________

Is b OK?

Donny

[Canadian45]

(b) is correct, but I would put a comma after "late".

She's always late, isn't she?