Which one of the following statements is correct?

1 Statement (A) is considered correct by the answer key. The National Song Vande Mataram was indeed composed by Bankimchandra Chatterji and appeared in his Bengali novel 'Anandamath'. While the language is highly Sanskritised, its origin in a Bengali literary work leads to it being described as originally in Bengali. 2 Statement (B) is correct. The National Calendar of India is based on the Saka era, and its first month, Chaitra, normally begins on 22nd March and on 21st March in a leap year. 3 Statement (C) is correct. The design of the National Flag of India was adopted by the Constituent Assembly on 22nd July 1947. 4 Statement (D) is correct. The song 'Jana-gana-mana', composed originally in Bengali by Rabindranath Tagore, was adopted in its Hindi version by the Constituent Assembly on 24th January 1950 as the National Anthem of India. 5 Since the provided answer is (A), the analysis focuses on justifying (A) while acknowledging the factual correctness of (B), (C), and (D). The emphasis in (A) is likely on the origin within a Bengali context.