Answer:
Correct answer is c: To the east, into what is now Japan.
Step-by-step explanation:
The founder of the Qin dynasty was the one that managed to unify whole China.
That is why the answers A, B and D are not correct as he unified this territories that are even today part of China. He even built a famous Chinese Wall.
What no Chinese ruler, including him never managed to do is to invade and conquer Japan. That is why option C is the correct one.