Concept:
India introduced the Product Patent regime through the Patents (Amendment) Act, 2005 to comply with the TRIPS Agreement of the World Trade Organization (WTO). Before 2005, India recognized only process patents for pharmaceuticals and agrochemicals.
Step 1: Recall the amendment.
The Patents (Amendment) Act, 2005 came into force on 1 January 2005, introducing product patents in India.
Step 2: Analyse the options.
• 2004 -- Incorrect.
• 2005 -- Correct.
• 2003 -- Incorrect.
• 2008 -- Incorrect.
Step 3: Final conclusion.
Hence, Product Patent was introduced in India in
\[
\boxed{2005.}
\]