Option 1: P. Mitra

There is no prominent leader of the Ghadar Party named P. Mitra. This option is incorrect.

Option 2: Lala Har Dayal

Lala Har Dayal was indeed a prominent leader of the Ghadar Party. He was a revolutionary and a nationalist who played a significant role in the Indian independence movement. He founded the Ghadar Party in 1913 with the aim of overthrowing British rule in India. Lala Har Dayal was known for his revolutionary ideologies and for inspiring many Indian revolutionaries.

Option 3: B.G. Tilak

Bal Gangadhar Tilak, also known as Lokmanya Tilak, was a prominent figure in the Indian independence movement, but he was not a leader of the Ghadar Party. This option is incorrect.

Option 4: Bipin Chandra Pal

Bipin Chandra Pal was a leader of the Indian nationalist movement, but he was not associated with the Ghadar Party. This option is incorrect.

Therefore, the correct answer is option 2: Lala Har Dayal, who was a prominent leader of the Ghadar Party.