Which of the following is not correct.
(i) Tenth Mandala describes about the four varnas known as Brahman, Kshtriya, Vaishya & Sudra.
(ii) Mundaka Upanishad describes the story of Yama & Nachiketa.
(iii) Atharva veda, Samveda and Yajurveda are collectively known as Trayee.
(iv) Krishna-Yajurveda comprises the description in prose.
a. ii & iii
b. i & iv
c. i & iii
d. iii & iv