Before any change is implemented, it must bedocumentedas part of change management procedures. This ensures transparency, review, and tracking.
FromQuentin Docter - CompTIA A+ Complete Study Guide:
"Documenting a change is the first step in change management. This includes defining the scope, purpose, impact, and implementation plan before approval or scheduling."

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.

At large events such as music festivals, cellular towers may become congested due to the high volume of users attempting to connect simultaneously. This congestion causes slow or failed data connections, which explains the email application being unable to sync or connect. This is a common real-world mobile connectivity issue in crowded areas.
A). Lack of storage would prevent saving attachments, not prevent connection attempts.
B). Company firewalls usually don't affect mobile access unless specific device restrictions are enforced.
D). Organizers do not have the ability to block the internet signal; only carriers manage mobile bandwidth.
Reference:
CompTIA A+ 220-1102 Objective 3.3: Troubleshoot mobile OS and connectivity issues.
Study Guide Section: Mobile network limitations - signal congestion and bandwidth issues

The correct answer is C. DDoS (Distributed Denial-of-Service), because the attack involves thousands of compromised machines, commonly referred to as a botnet, generating fraudulent traffic against an online service. Although the activity includes fake purchases, the scale and distributed nature indicate an attempt to overwhelm or disrupt the service.
According to the Quentin Docter - CompTIA A+ Complete Study Guide, DDoS attacks use multiple systems to flood a target with traffic, exhausting server resources and preventing legitimate users from accessing the service. These attacks often involve compromised devices controlled remotely.
The Travis Everett & Andrew Hutz - All-in-One Exam Guide explains that DDoS attacks can take many forms, including HTTP request floods and application-layer attacks that mimic legitimate user actions, such as fake transactions.
The Mike Meyers / Mark Soper Lab Manual clarifies that brute-force attacks focus on credential guessing, spoofing involves identity falsification, and SQL injection targets database queries. None of those specifically require thousands of compromised machines.
Because the defining characteristics here are scale, distribution, and coordinated malicious activity, the correct classification is a DDoS attack, making C the correct answer.

Keychainis the built-in macOS utility that manages and stores credentials, including passwords and certificates.
According toQuentin Docter - CompTIA A+ Complete Study Guide:
"Keychain Access in macOS is used for managing and storing passwords securely, similar to credential managers in Windows."