"Work out" vs "Work on"

[Zinna]

English Language Tests, Intermediate level

ESL/EFL Test #200 "Phrasal Verbs (T to W)", question 7

Lilly likes to ......... early in the morning so that she's fit for work.

(a) work on
(b) work over
(c) work out

English Language Tests, Intermediate level

ESL/EFL Test #200 "Phrasal Verbs (T to W)", answer 7

Lilly likes to work out early in the morning so that she's fit for work.

Correct answer: (c) work out

Your answer was: incorrect
Lilly likes to work on early in the morning so that she's fit for work.
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why not "work out"?

Zinna

[Alan]

Hi,

Work out is the correct answer and means to do/take physical exercise. Work on means either concentrate on or continue to work.

Alan
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English as a Second Language
You can read my ESL story Present Simple

[Saneta]

so that she's fit for work=so that she is fit for work=so that she is in good condition/in a good condiotion/athletic for work?

'a' before 'condition'?

thanks