In the question given below, the sentence/part of the sentence is in bold. Five alternatives are given for the bold words. Choose the correct alternative that will improve the sentence or mark the option corresponding to it. Choose option 5 if no improvement is required.
The letter was being written by Samuel as a reply to his superior.
1
been written by
2
be written by
3
to be written by
4
to being written by
5
No improvement is required