There are 4 options:
a. Melanie wrote to her sister once a week while she was living abroad.
b. While her sister was living abroad, Melanie wrote to her once a week.
c. When traveling abroad, a letter was written once a week by Melanie to her sister.
d. Her sister received a letter once a week from Melanie while she was living abroad.
The correct answer is b, while I chose a.
So my questions are:
- What is the 'she' referring to in each of option?
- Why is option 'a' wrong?