Which of the following could potentially be introduced at the time of side loading?

Sideloading involves installing applications from sources other than official app stores. This process bypasses security checks, making it a common vector for introducing malware, including rootkits. A rootkit is a collection of software tools that enables unauthorized access to a computer or area of its software and is typically hidden from detection. User impersonation is a social engineering technique, not directly introduced by sideloading. An on-path attack (formerly man-in-the-middle) intercepts communication between two parties and is a network attack, not an application installation issue. A buffer overflow is a type of software vulnerability, not a type of malware introduced by sideloading, although sideloaded software could contain a buffer overflow vulnerability.