Kshetragna is renowned as a composer of Padams, which are lyrical compositions usually set to slow tempo and express devotional or romantic themes.
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Explanation of Other Options:
(B) Mysore Vasudevachar: Famous for varnams and kritis, not primarily Padams.
(C) Annamacharya: Known for devotional keertanas, mainly Telugu compositions.
(D) Patnam Subramanya Iyer: Noted for kritis, not Padams.
Hence, the correct answer is option (A).