What did russia do in response to austria declaring war on serbia?
how did it affect germany?

answer: in response to austria's declaration of war, russia, serbia's ally, began moving its army toward russian-austrian border. expecting german to join austria, russia also mobilized along to german border. the german, russia's mobilization amounted to a declaration of war. on august 1, the german government declared war on russia

the answer is title i subtitle b

i would go with the last one