The Open Web Application Security Project (OWASP) Zed Attack Proxy (ZAP) is a specialized, open-source tool designed specifically for finding vulnerabilities in web applications. It functions as an intercepting proxy and an automated scanner, making it highly effective for identifying common web-based security flaws. The question explicitly lists SQL injection, path traversal, and cross-site scripting, which are core vulnerabilities that OWASP ZAP is built to detect. Given the context of testing a beta web application, ZAP is the most appropriate and recommended tool for the development team to use for a quick and targeted assessment.

A. Hashcat: This is a password recovery and cracking tool used to discover passwords from their hash values; it does not scan for web application vulnerabilities.
B. OpenVAS: This is a comprehensive network vulnerability scanner that primarily identifies issues at the operating system and service level, not deep application-layer flaws.
D. Nmap: This is a network exploration tool and port scanner used for network discovery and security auditing, not for detailed web application vulnerability analysis.

1. OWASP Foundation. (n.d.). The OWASP Zed Attack Proxy Project. OWASP. Retrieved from https://owasp.org/www-project-zed-attack-proxy/. The official project page states, "It can help you automatically find security vulnerabilities in your web applications while you are developing and testing your applications." This directly aligns with the scenario.

2. CompTIA. (2022). CompTIA Analyst+ (CS0-003) Exam Objectives. Version 3.0, Section 2.2. The objectives list various vulnerability scanners, implicitly categorizing tools like ZAP as web application scanners, distinct from network scanners like Nmap, which is listed under "Network enumeration."

3. Pound, J., & Ali, S. (2018). Web Application Security. In Proceedings of the 2018 ACM SIGCSE Technical Symposium on Computer Science Education (p. 1096). Association for Computing Machinery. DOI: https://doi.org/10.1145/3159450.3162258. This academic publication discusses tools for teaching web application security, noting that "OWASP ZAP is a popular open source tool for finding vulnerabilities in web applications" and is used to demonstrate attacks like XSS and SQL injection.