Directions: Which of the following phrases given below in the options should replace the phrase that is underlined in the sentence to make it grammatically correct? If the sentence is correct and does not require any correction mark 'No correction required' as your answer.

Q:

Amazon Inc.'s self-driving vehicle unit, Zoox, has successful testing a robotaxi with employees as passengers on a public road.

• 1
  has been testing
• 2
  have success tested
• 3
  has successfully tested
• 4
  was testing successful
• 5
  No correction required