The correct answer is C. Tirhut.
Ghiyasuddin Tughlaq was the founder of the Tughlaq dynasty of the Delhi Sultanate. He was born in 1266 CE in Turkistan and came to India in 1296 CE. He ascended the throne of Delhi in 1320 CE.
Ghiyasuddin Tughlaq was a powerful and ambitious ruler. He wanted to expand his empire and he invaded many regions in India. In 1324 CE, he invaded the region of Tirhut. Tirhut was a region in the eastern part of India, which is now part of the state of Bihar.
Ghiyasuddin Tughlaq’s invasion of Tirhut was successful. He conquered the region and annexed it to his empire. The invasion of Tirhut was a major turning point in the history of the Tughlaq dynasty. It marked the beginning of the Tughlaq dynasty’s expansion into the eastern part of India.
The other options are incorrect. Gaya is a city in the state of Bihar. Bhojpur is a district in the state of Bihar. Patna is the capital of the state of Bihar.