Biotic factors are organisms that interact with non-living & living parts of an ecosystem.
Egs. badgers, worms, fungi, bacteria, insects.
I think it is C. However, it should just be rock and water/ice.
Found at the lowest point of a large drainage area, these seasonal, marsh-like ponds collect and store water from rain and runoff. Unlike vernal pools, playas generally fill when temperatures are unsuitable for plant growth, and often the water is salty, alkali or both.
source- google
The correct answer is D. Decreased travel times.
The industrial revolution revolutionized the transport as well, so in this period we have the emergence of transporting machines, like the trains for example, and they were also getting better and better as the year passed by, and they were of great help to the people, especially when they had to travel on long distances.
