The correct answer is: A. 1324.
Ghiyasuddin Tughlaq invaded Bengal and Bihar in 1324. He was the founder of the Tughlaq dynasty of the Delhi Sultanate. He was a powerful and ambitious ruler who sought to expand his empire. He invaded Bengal and Bihar in order to bring these regions under his control. The invasion was successful, and Ghiyasuddin Tughlaq was able to establish his authority in these regions.
The other options are incorrect. Option B, 1320, is the year in which Ghiyasuddin Tughlaq ascended to the throne of the Delhi Sultanate. Option C, 1319, is the year in which Ghiyasuddin Tughlaq invaded Gujarat. Option D, 1318, is the year in which Ghiyasuddin Tughlaq invaded Malwa.