Why was Bengal excluded, Supreme Court asks Centre

The Supreme Court asked the Centre why did it single out Assam and exclude West Bengal from grant of citizenship under section 6A of the Citizenship Act when the latter shares a much larger border with Bangladesh. Section A of the Citizenship Act relates to illegal immigrants in Assam. Observing that illegal immigration is a serious problem, a five-judge Constitution bench headed by Chief Justice DY Chandrachud asked Solicitor General Tushar Mehta, appearing for the Centre, what is the Union government doing to safeguard the border. During the hearing, the CJI remarked that there were people who benefited from the grant of citizenship under Section 6A.