It's being estimated that dinosaurs lived on Earth from about 237 million years ago to about 66 million years ago. So answers B and D are definately too "old", while answer A is too "young". I'd pick answer C as it's most probable.
b. Original horizontality
Hope this helps!
I think the two sources would be drip irrigation which is like a river, lake, groundwater, etc... The second source could be is making a new irragation system that could deliver water faster.
The largest coral reef is the Great Barrier Reef, located in the Coral Sea, off the coast of Queensland, Australia