Which one of the following colours may be obtained by combining green and red colours?

The combination of green and red light is a fundamental principle of the additive color mixing model, commonly known as the RGB (Red, Green, Blue) model. In this system, red, green, and blue are the primary colors of light [1]. When red and green light are combined additively, they produce the secondary color yellow [1]. This process is widely utilized in technologies such as computer monitors, television screens, and stage lighting. While mixing red and green pigments (subtractive mixing) typically results in a dark brownish hue, the question refers to the standard physics of light where R + G = Y. Other secondary colors in this model include cyan (green plus blue) and magenta (red plus blue) [1]. Therefore, yellow is the correct resultant color when combining red and green light.

Sources

1. [1] https://www.sciencedirect.com/topics/engineering/mixing-color