The correct answer is option 3, which states that the method followed in electing the President of India is Proportional Representation and the Single Transferable Vote (STV) System.

Let`s dissect the other options to understand why they are not correct:

Option 1 states that only Proportional Representation is followed in electing the President of India. This is incorrect because the process also involves the Single Transferable Vote (STV) System.

Option 2 states that only the First-Past-the-Post System is followed. This is incorrect because the First-Past-the-Post System is not used in the election of the President of India.

Option 4 states that both Proportional Representation and the First-Past-the-Post System are followed in the election of the President of India. This is incorrect because the election process only involves Proportional Representation and the Single Transferable Vote (STV) System.

Therefore, the correct answer is option 3, as it accurately reflects the methods used in electing the President of India.