Step 1: Identify the tense of the passive sentence. “has been bought” is the Present Perfect Passive. The agent is 'me'.
Step 2: Convert to active voice. The agent 'me' becomes the new subject 'I'. The passive subject 'A new car' becomes the active object.
Step 3: Change the verb form. The Present Perfect Passive ('has been bought') changes to the Present Perfect Active ('have bought' for the subject 'I').
Step 4: Form the active sentence. The correct sentence is: "I have bought a new car."