What is an exception for controlled substance violations under INA 237(a)(2)(B)(i)?

The choice involving a single offense with 30 grams of marijuana for personal use is correct because it reflects a specific exception in the Immigration and Nationality Act (INA) regarding controlled substance violations. INA 237(a)(2)(B)(i) generally allows for deportation of non-citizens with drug convictions; however, it includes an exception for individuals who have committed a single offense related solely to the possession of a small amount of marijuana for personal use. This means that such individuals would not face the same legal repercussions as those involved in larger-scale drug offenses or multiple violations.

The other options do not qualify as exceptions under this provision since they either involve larger quantities or are related to broader drug-related convictions, none of which meet the specific criteria that would result in exemption from deportation under the specified section of the law. For instance, a conviction involving a large quantity of drugs would certainly lead to more severe consequences and would not fall under the exception meant for personal use.