Answer:
Option A, current scientific knowledge
Step-by-step explanation:
New scientific discoveries are based on the existing/current scientific knowledge. Knowledge/research/new discovery is inevitable and thus it is continuously tested and trialed thereby leading to emergence of new concepts and theories for same existing fact. All the existing scientific concepts and theories can be refined based on the new interventions but discarding an existing theory completely is non viable.
For example - Scientist found that atom was the smallest unit of matter. With further discoveries in the later layers, it was found that it is the electron, proton and neutron which is the smallest unit of matter, and now the current discoveries shows that there are particles even smaller than electron such as meson and thus meson should be considered as smallest unit of matter.