I believe the answer is B - point source comes from a specific site, non-point comes from many sources
First of all the reason the graph would be a curve is because, as the time increases the position changes, at first the ball is at a certain point then it starts rolling off a cliff so its moving foward and then the ball starts falling, (If too confusing here is a image http://www.mazzworld.net/U11Image1.gif)
This is Russia we're talking about, so there are bound to be a few minor extremes between seasonal temperatures.
Winters last fron November to March and are usually very cold. Temperatures often drop below freezing.
Summers are from May to August and are usually at a comfortable 70-80 degree range. Heatwaves can raise temperatures up to above 86 degrees.