Why are the seasons opposite in the northern and southern hemispheres

Great question!

That is because they are on opposite sides of our planet. If one side is illuminated, then the other side must be shadowed. So the Earth alternates between

Northern hemisphere tilted toward the Sun, southern hemisphere tilted away from the Sun

and

Northern hemisphere tilted away from the Sun, southern hemisphere tilted toward the Sun

answer; //the above statement is (false);

where is the diagram?

if you insert the diagram ill be able to you