Scientist define the beginning and end of time periods based on: A. equal amounts of time.
B. The appearance and disappearance of index fossils.
C. solar changes. D. sediment changes.

the question isn't complete here so i can't right an answer '_'

i dont know it at allnow im just getting points at this pint

sodium i think the chemical element of atomic number 11, a soft silver-white reactive metal of the alkali metal group.

that would be called plucking : )

explanation:

''plucking, also referred to as quarrying, is a glacial phenomenon that is responsible for the erosion and transportation of individual pieces of bedrock, especially large "joint blocks". as a glacier moves down a valley, friction causes the basal ice of the glacier to melt and infiltrate joints (cracks) in the bedrock."