Pluto was once classified as a planet. however, scientists no longer classify pluto as a planet. which is a likely reason for this change?
the original hypothesis about pluto was supported.
no observations of pluto were made in the past.
several planets in outer space were found to be similar to pluto.
there were significant changes in scientific knowledge about planets.

The phlogiston theory in the 17th century attempted to explain burning. the theory stated that combustable objects contained a material called phlogiston, a substance without mass, color, odor, etc. after objects burned, the objects were dephlogistonated and were then in their true form. the phlogiston theory was accepted until the 18th century, when lavoisier proved that combustion requires a gas that has mass. phlogiston is considered a) to be scientific knowledge b) not to be scientific knowledge c) to be proven by scientific method d) to be accepted in the modern scientific community

Amale bird-of-paradise uses a dance to attract mates in which it flaps its tail feathers on the ground and jumps around a potential female mate. a different male bird-of-paradise does a similar dance but it jumps around the female in the opposite direction. the female bird is only attracted to one style of dance, in one direction. this is an example of speciation.

Development has provided electrically for less money but what may be considered a cause of nuclear power