Do these actions co-occur?

[Rahel]

English Language Tests, Intermediate level

ESL/EFL Test #173 "Simple Present, Simple Past, Simple Future", question 4

When she was younger, my grandmother ......... in a mortuary.

(a) works
(b) will work
(c) worked

English Language Tests, Intermediate level

ESL/EFL Test #173 "Simple Present, Simple Past, Simple Future", answer 4

When she was younger, my grandmother worked in a mortuary.

Correct answer: (c) worked

Your answer was: correct
_________________________

we use when to introduce the action that starts first

Rahel

[Mister Micawber]

.
No, the actions co-occur.
.
_________________
Canadian-American native speaker
who teaches English for a living at Mister Micawber's
ESL cafe: Interview with Mister Micawber