The sun rays are received by the plants and explell oxygen and we breath the oxygen to be able to survive
The correct answer is C: the gravitational forces due to the sun and the moon cancel each other's effect.
A scientific theory is a well-tested explanation for a wide range of observations or experimental results. A hypothesis is a possible answer to a question.
The question must refer to the modern classification system in biology.
It started with the work of Linnaeus - so its early version can be called a Linnaean classification - but right now it has been expanded and changed to fit the evolutionary relationships between the species - which is the best description, i.e. the answer is "it is based on the evolutionary relationship of the species"
