Which was the first monochrome film to be fully converted into colour in 2004?

To answer this question, the user needs to know about the history of Indian cinema and the process of colorization of monochrome films.

Option A: Mughal-e-Azam is a 1960 Indian epic historical drama film directed by K. Asif and produced by Shapoorji Pallonji. Although it was not the first Indian film to be colorized, it was colorized in 2004 by a team of technicians at the Indian office of the American production house, Prism.

Option B: Raja Harishchandra is a 1913 Indian silent film, directed and produced by Dadasaheb Phalke. It is considered to be the first full-length Indian feature film and is shot in monochrome. It was not converted into color.

Option C: Sahib Biwi aur Ghulam is a 1962 Indian Hindi film directed by Abrar Alvi and produced by Guru Dutt. It was not the first Indian film to be colorized.

Option D: Naya Daur is a 1957 Indian sports drama film directed and produced by B. R. Chopra. It was colorized in 2004 by a Mumbai-based company.

Therefore, the answer is: A. Mughal-e-Azam.