The Hindu is (1)/ most popular, than any other (2)/ newspaper in India.(3)/ No error (4)

Answer

2

Explanation

more will replace most because
Comparison has been made here.
Hence, more popular than any other is the right usage.
have will replace am having because - haveis a stative verb that usually relates to thoughts, emotions, relationships, senses, states of being and measurements. These Verbs are notused in Contin- uous Tenses
Simple Tenses are used for them.
Look at the examples given below
She has a Mercedes. (She owns It.) ,
She is having lunch. (Sheis eating)
Some stative Verbs are : agree, appear, seem, be, feel, see, etc