What type of scanning indicator completes two vertical scan periods to produce one complete picture called a frame?

The concept of scanning indicators is essential in understanding how images are produced on screens. A raster scanning system is one of the most common techniques used in video displays, including televisions and computer monitors.

In a raster scan, the display system moves the electron beam (or equivalent technology in modern displays) horizontally across the screen from left to right, beginning at the top and moving downwards. Each horizontal line is scanned one after the other until all lines of the image are completed, forming a complete picture known as a frame. Importantly, the raster scan consists of two vertical scan periods – one for even lines and another for odd lines – which allows the display to refresh the full image quickly and effectively while utilizing the persistence of vision.

This technique is fundamental to the way most electronic displays operate, making it the correct answer to the question about completing two vertical scan periods to produce one complete picture or frame.