'शिक्षक विद्यार्थ्यांना गणित शिकवतात.' या वाक्यातील प्रयोग बदलायचा असेल, तर पुढीलपैकी कोणता पर्याय योग्य ठरेल ?

The correct answer is Option C (Shikshakanni vidyarthWestern ganit shikavave.).

Key Points:
• The original sentence 'शिक्षक विद्यार्थ्यांना गणित शिकवतात' is in Kartari Prayog (active voice), where the verb agrees with the nominative subject 'शिक्षक'.
• To change the voice (प्रयोग रूपांतर), the subject must not remain in the nominative case (प्रथमा विभक्ती). Options (1), (2), and (4) retain 'शिक्षक' in the nominative case, merely changing the tense or aspect (all remaining Kartari Prayog).
• In option (3) 'शिक्षकांनी विद्यार्थ्यांना गणित शिकवावे', the subject is inflected with the instrumental suffix (-नी), shifting the construction out of Kartari Prayog into Vidhyarthi Karmani/Bhave construction.
• Thus, option (3) is the only valid change of voice.
• Key Takeaway: Transforming voice requires altering the case of the subject; simple tense alterations without case change remain Kartari.