To answer this question, you need to understand the concept of custom controls in programming.
Option A) The Paint() method - This option is incorrect. The Paint() method is used to specify the custom drawing behavior of a control, but it is not required to be overridden in a custom control.
Option B) The Control_Build() method - This option is incorrect. There is no Control_Build() method in the context of custom controls.
Option C) The Render() method - This option is correct. The Render() method must be overridden in a custom control. It is responsible for rendering the control's visual representation.
Option D) The default constructor - This option is incorrect. The default constructor is not specific to custom controls and does not need to be overridden.
The correct answer is C) The Render() method. This option is correct because the Render() method is required to be overridden in a custom control to define how the control should be rendered visually.