Scenario: A technology startup has rapidly expanded and is experiencing challenges with its current flat organisational structure, including frequent miscommunications and delayed decision$-$making. Considering the need for clearer hierarchy and improved coordination, which organisational structure adjustment would best support the startup's evolving needs?

A$.$ Transitioning to a more hierarchical structure to define clear lines of authority and responsibility.

B$.$ Maintaining the flat structure but increasing the number of employees to manage the workload.

C$.$ Adopting a matrix structure to enhance flexibility and maintain the flow of information.

D$.$ Implementing a network structure to outsource non$-$core functions and focus on key areas.