In which year Lithuania became the first of the 15 Soviet Republics to declare its independence?

March 1990

The correct answer is option (3) - March 1990

In 1988 Independence movement began in Lithuania and later spread to Estonia and Latvia.
Lithuania became the first of the 15 Soviet republics to declare its independence in March 1990.
The three Baltic republics of Estonia, Latvia, and Lithuania became UN members in September 1991.
Three Baltic republics of Estonia, Latvia and Lithuania joined NATO in March 2004.