Q:

Identify the appropriate choice in changing the voice of the following sentences.
 India had eradicated smallpox by 1975.

• 1
  Smallpox was eradicated by India by 1975.
• 2
  Smallpox were eradicated by India by 1975.
• 3
  Smallpox had been eradicated by India by 1975.
• 4
  Smallpox would have been eradicated by India by 1975.