The best answer is B. The river flooded yearly which allowed the fertile sediment on the bottom of the river to flow onto the farmland, keeping it fertile.
A good index fossil is one with four characteristics: it is distinctive, widespread, abundant and limited in geologic time. Because most fossil-bearing rocks formed in the ocean, the major index fossils are marine organisms. That being said, certain land organisms are useful in young rocks and specific regions.
MaryEtta's belief correspond to "trait approach".
The trait approach was one of the principal deliberate endeavors to consider administration. In any case, the term characteristic has been the wellspring of extensive uncertainty and perplexity in the writing, alluding at times and differently to identity, personalities, miens, and capacities, and to any persevering characteristics of the individual, including physical and statistic properties.
Hey There!
So The Force That Always Pulls Downwards In Called Gravity. Gravity Is Constantly Pushing Down On Us. If Gravity Wasn't There, Then We Would Be Floating In Air.
Hope That Helps,
~Spades15