Comprehensive and Detailed Explanation From Exact Extract:
Smishing (SMS phishing) is a type of social engineering attack where attackers send fraudulent text messages to trick users into revealing sensitive information or downloading malware. These messages often impersonate banks, delivery services, or official institutions to lure the victim into clicking malicious links.
A: Impersonation is an in-person or voice-based tactic.
B: Vishing refers to voice phishing over phone calls.
C: Spear phishing is a targeted email-based phishing method.
Reference:
CompTIA A+ 220-1102 Objective 2.3: Compare and contrast social engineering techniques.
Study Guide Section: Smishing as a type of phishing via SMS or mobile messaging.

The correct answer is C. Change the User Account Control (UAC) settings, because the credential prompt during installation indicates that the system is requesting administrative privileges. In Windows environments, UAC is designed to prevent unauthorized system changes by prompting for administrator approval when elevated permissions are required.
According to the Quentin Docter - CompTIA A+ Complete Study Guide, UAC acts as a security boundary between standard user activities and system-level changes such as software installation. If a user does not have sufficient privileges, the system will request administrator credentials before proceeding.
The Travis Everett & Andrew Hutz - All-in-One Exam Guide explains that technicians can temporarily adjust UAC settings or provide proper elevation to allow legitimate installations. This is especially common in corporate environments where users operate with standard accounts.
The Mike Meyers / Mark Soper Lab Manual reinforces that restarting the computer or using a different browser does not change permission requirements. Contacting the software vendor is unnecessary when the issue is clearly related to local security controls.
Because the installation is blocked by privilege restrictions enforced by UAC, adjusting User Account Control settings or providing proper elevation is the correct and most efficient resolution, making C the correct answer.

Comprehensive and Detailed Explanation From Exact Extract:
Whalingis a form of phishing that targets high-profile individuals or involves pretending to be them (e.g., CEOs) to trick lower-level employees into transferring funds or sensitive data.
FromQuentin Docter - CompTIA A+ Study Guide:
"Whaling is a phishing tactic targeting executives or masquerading as one. The attacker crafts emails that exploit authority and urgency to manipulate recipients."

Comprehensive and Detailed Explanation From Exact Extract:
Group Policyis the standard administrative tool for enforcing security and configuration settings across domain-joined systems, including disabling guest accounts.
FromQuentin Docter - CompTIA A+ Study Guide:
"Disabling guest accounts and applying consistent security policies across multiple machines is best achieved through Group Policy on a Windows domain."