well, because it's an 'explain' question, you will NEED quite a lot of words. you have to describe all the things that both Br and G did (separately, because htey both did different things) and then talk about how that would have increased their material & military strength in both issues, separately. so you should have 4 columns of points to raise.
to give you a start, there are all things like
DORA,
conscription
rations
gov't spending
factories
propaganda dep'ts
newspaper censorship
really, it's everything that happened in the war to make it good. just make sure you differentiate everything into the columns, - germany mlitary, germany material, britain military, britain material.
look at the bos definitions of explain - it's show cause and effect? or something, make sure you do that. so talk about the results of each country's effects