The correct option is C.
Locks are designed in such a way that they have a double pair of huge gates and they are used to raise and lower ship as they pass through the Panama canal. The Panama canal allows ships to travel between the Pacific and the Atlantic ocean.
It depends on the shape of the stones. If the stones are in the shape of an arrowhead, then yes, they are evidence of early humans. If not, it could be just a piece of broken rock.
If a nation is very small they could only accept a certain amount of people. They are small so they only have so much food, space, etc. to provide for its citizens. Though if the nation was large such as the US or Canada they can be a little less strict and allow more people in.
