The correct answer is: B. Three puppies were rescued by Rita.
This is because the sentence is in the past tense. The verb “rescued” is in the past tense, which indicates that the action of rescuing the puppies has already been completed.
The other options are incorrect because they are not in the past tense. Option A, “Three puppies are rescued by Rita,” is in the present tense. This would be correct if the sentence were about Rita rescuing puppies on a regular basis. Option C, “Three puppies will be rescued by Rita,” is in the future tense. This would be correct if the sentence were about Rita planning to rescue puppies in the future. Option D, “Three puppies are being rescued by Rita,” is also in the present tense. This would be correct if the sentence were about Rita currently rescuing puppies.
In conclusion, the correct answer is: B. Three puppies were rescued by Rita.