In May 1998, while addressing at nuclear tests site near Pokhran, who added 'Jai Vigyan' to the Lal Bahadur Shastri's slogan 'Jai Jawan, Jai Kisan' ?

A) Indira Gandhi
B) Rajeev Gandhi
C) P.V.Narsimha Rao
D) Atal Behari Vajpayee

Answer : D