I heard him (play) the piano.

• সঠিক উত্তর হচ্ছে - ক) play এবং গ) playing.
- অর্থাৎ, Both A + C

• Complete sentence:
- I heard him play the piano.
- I heard him playing the piano.

• কিছু কিছু verb আছে, যাদের পরে infinitive (to) উহ্য থাকে,  verb এর present form বসে এবং এদের সাথে (verb+ing) এর ব্যবহারও সঠিক। 
- এই verb গুলো হচ্ছে - Feel, hear, see, watch, notice, find.
• Hear, see, feel, watch, notice, find etc. + object + infinitive or -ing/ Hear or see someone/something to do something:
- We can use either the infinitive without to or the -ing form after the object of verbs such as hear, see, notice, and watch. 

• Here are some  examples demonstrating the use of bare infinitives (without "to") or gerunds (-ing form) after verbs like feel, hear, see, watch, notice, and find:
• Feel:
- I felt the earth shake. (bare infinitive)
- I felt my heart racing. (gerund)

• Hear:
- I heard him sing. (bare infinitive)
- We heard the children laughing. (gerund)

• See:
- I saw her leave the building. (bare infinitive)
- I saw them playing in the park. (gerund)

• Watch:
They watched the sun set. (bare infinitive)
They watched the chef cooking. (gerund)

• Notice:
Did you notice him arrive? (bare infinitive)
I noticed her smiling at me. (gerund)

• Find:
We found the key lying on the floor. (gerund)
I found myself agree with her. (bare infinitive)