Option 1: B.J.P. stands for Bharatiya Janata Party. However, the question asks about a party that provided two Prime Ministers in two years. At the time of writing this explanation, the Bharatiya Janata Party has not provided two Prime Ministers in a span of two years. Therefore, option 1 is incorrect.

Option 2: Janata Party is the correct answer. The Janata Party, a political party in India, provided two Prime Ministers in a span of two years. Morarji Desai served as the Prime Minister from 1977 to 1979, and Charan Singh served as the Prime Minister for a brief period in 1979. Thus, option 2 is the correct answer.

Option 3: Janata Dal is another political party in India, but it did not provide two Prime Ministers in two years. Hence, option 3 is incorrect.

Option 4: Samajwadi Janata Party is a regional political party in India, and it did not provide two Prime Ministers in two years. Therefore, option 4 is incorrect.

In conclusion, option 2, Janata Party, is the correct answer as it provided two Prime Ministers in a span of two years.