Institution: SONALI BANK LTD Exam: Sonali Bank Ltd - Assistant Programmer - 26.08.2016 ||
Topic: ICT (তথ্য ও যোগাযোগ প্রযুক্তি), Subject: Computer and ICT (তথ্য ও যোগাযোগ প্রযুক্তি)

Best Answer Explained in Below-:

DQL Injection, or Database Query Language Injection, is a type of security vulnerability that allows an attacker to manipulate a database query by inserting malicious code into input fields. To avoid DQL Injection, the most effective strategy is **C) using careful programming**. This approach emphasizes the importance of secure coding practices, such as parameterized queries and prepared statements.

By implementing these techniques, developers can ensure that user inputs are treated as data rather than executable code. For instance, parameterized queries allow parameters to be bound to the SQL statement separately, which prevents an attacker from altering the structure of the query itself. Furthermore, validating and sanitizing inputs before processing them significantly reduces the risk of malicious data being inserted into database commands.

While firewalls (option A) and virus protection (option B) can provide additional layers of security, they do not specifically address the root cause of DQL Injection vulnerabilities—unsafe coding practices. Thus, careful programming is crucial for creating resilient applications and safeguarding against DQL Injection attacks.