Question

Which of the following is true about shifts in scientific knowledge?

Answer 1

Major shifts, that is shifts in the paradigms, are not very frequent - they would make scientific research unstable, as any result of a smaller study could be made invalid by a paradigm shift,

minor changes however are quite common - basically every scientific study adds to the common knowledge and this also can be considered a minor change.

Therefore the best answer is
Major shifts in scientific views very rarely occur, but minor modifications of prior knowledge are continually made based on new research.