Bioluminescence is the production and emission of light by a living organism. Among the given options, only stars and fireflies emit their own light but stars are not living objects and butterflies and bees do not emit light. So firefly is an example of bioluminescence.

Objects which emit light on their own are known as luminous objects. For example, candle, gas flame etc emit light of their own. So any kind of flame is luminous.

The shape of a shadow depends on the shape of the object and on the orientation of the source of light with respect to the object. For example, the shadow of a cube can be rhombus, square or rectangle depending on the orientation of source of light. In addition, the size will depend upon the distance between the object and the source of light.

Pinhole camera always forms inverted image only. The reason we don't see the image of the sun inverted is that the image is very small and it is highly symmetrical (the sun itself is spherical and symmetric). So, being inverted or not it appears to be the same.

Shadows are formed when an object blocks the light. The screen is necessary for the shadow to be projected (which is just the absence of light) and only after that, a shadow is visible.