Among the options provided, fingerprint scanning has the highest rate of false negatives. False negatives occur when a biometric system fails to recognize an authentic individual. Factors such as skin conditions (wet, dry, greasy), finger injuries, and inadequate scanning can contribute to false negatives in fingerprint scanning1. In comparison, iris recognition23, face recognition45, and retina scanning67 generally have lower rates of false negatives.
References:
How Accurate are today's Fingerprint Scanners? - Bayometric
25 Advantages and Disadvantages of Iris Recognition - Biometric Today
Iris Recognition Technology (or, Musings While Going through Airport ...
The Critics Were Wrong: NIST Data Shows the Best Facial Recognition Algorithms Are Neither Racist Nor Sexist | ITIF NIST Launches Studies into Masks' Effect on Face Recognition Software Retinal scan - Wikipedia How accurate are retinal security scans - Smart Eye Technology

An outsourced accounting application has the most inherent risk and should be prioritized during audit planning because it involves external parties, sensitive data, and complex transactions that are susceptible to material misstatement, error, or fraud12. An outsourced accounting application also requires more oversight and monitoring from the internal audit department to ensure compliance with the service level agreement and the organization's policies and standards3.
References
1: Inherent Risk: Definition, Examples, and 3 Types of Audit Risks 2: 3 Types of Audit Risk - Inherent, Control and Detection - Accountinguide 3: IS Audit Basics: The Core of IT Auditing

Due professional care is the obligation of an IS auditor to exercise the appropriate level of skill, competence, and diligence in performing an audit. It also requires the IS auditor to comply with the relevant standards, guidelines, and ethical principles of the profession. Completing an engagement by email only may compromise due professional care, as it may limit the IS auditor's ability to obtain sufficient and appropriate evidence, to communicate effectively with the auditee and other stakeholders, and to perform adequate quality assurance and review procedures. The other options are not as relevant as due professional care, as they relate to specific aspects of an audit, such as proficiency (the knowledge and skills of the IS auditor), sufficient evidence (the quantity and quality of the audit evidence), and reporting (the presentation and communication of the audit results). References: CISA Review Manual (Digital Version), Domain 1: The Process of Auditing Information Systems, Section 1.2 ISACA IT Audit and Assurance Standards