Well let's take Sedimentary rock for example, The Law of Superposition which measures the average age of Sedimentary rocks using rocks around it. So you would use that rocks below it are older and that Extrusions and Intrusions are younger than the rocks which are stable.
Answer:
I think C.............................
Xylem tissue makes up a root organ
C. The nucleus does not exit within a prokaryotic cell
The answer is option B "declining number and variety of the species in an area." Biodiversity is a variety of life for example a ecosystem has many species which makes it a biodiversity. Now a loss of a biodiversity would be loosing a huge amount of species in that area or ecosystem which would mean the answer is option B.
Hope this helps.
