Option 1: Lala Lajpat Rai was a prominent Indian nationalist leader and a founding member of the Indian National Congress. However, he was not directly associated with the foundation of the Ghadar Party.

Option 2: Lala Hardyal is the correct answer. He was one of the key founders of the Ghadar Party, which was established in 1913 in San Francisco, USA. The party aimed to achieve Indian independence from British colonial rule through armed revolution.

Option 3: C.R. Das, also known as Deshbandhu, was a notable Indian politician and a prominent leader in the Indian National Congress. He played a significant role in the Indian independence movement, but he was not directly associated with the foundation of the Ghadar Party.

Option 4: Bipin Chandra Pal was one of the key leaders of the Indian independence movement. He advocated for self-governance and was a prominent member of the moderate faction within the Indian National Congress. Although he had similar ideals to the Ghadar Party, he was not directly involved in its foundation.

In conclusion, Lala Hardyal was the key figure associated with the foundation of the Ghadar Party.