Which of these would not be a valid scientific theory?
a all cells come from pre-existing cells.
b humans originated on earth from outer space.
c the universe is expanding at a constant rate.
d at one time, all of earth's continents were one large land mass.

B Humans originated on earth from outer space.

Explanation:

A scientific theory can be define as the explanation for a phenomena which naturally occur. It is supported and verified by using observatory approach and using appropriate scientific methodology required to obtain the results which are expected to prove the facts.

B Humans originated on earth from outer space. is not a valid scientific theory this is because of the fact that on the basis of many proposed scientific theories and literature the human species was originated on earth and not from the outer space.

you must remain stopped until the stop signal is retracted and the red lights are turned off. approaching traffic in the opposite roadway of a divided highway shall not be required to stop, even if the school bus has the stop-arm extended and the alternately flashing warning signal lamps on.