प्र:

Identify the appropriate choice in changing thr voice of the following sentences. She was knitting a sweater at that time.

• 1
  A sweater was being knitted by her at that time.
• 2
  A sweater was being knitted by her at this time.
• 3
  She knitted a sweater at that time.
• 4
  A sweater has been knitted by her at that time.