Answer:
It is the first option,
My grandmother, by the way painted these beautiful watercolors.
Step-by-step explanation:
The rest don't make sense in speech, there would have to be pauses at irregular times for the others.
My grandmother, by the way, painted these beautiful watercolors.
Normally I would have said "By the way, my grandmother painted these beautiful watercolors." But that wasn't an option so I think it's the first one
1.6m questions
2.0m answers