Final answer:
Sally, who works in HR, is responsible for managing holiday requests, payroll inquiries, complaints about colleagues, and office supplies requests for the employees at the company.
Step-by-step explanation:
The employee who can send holiday requests, payroll inquiries, complaints about colleagues, and office supplies requests is Sally. Since Sally works in HR (Human Resources), she is responsible for managing employee requests and concerns, including holidays, payroll, complaints, and office supplies.
She is the point of contact for employees regarding these matters and will handle the necessary processes and communication.