John's success has nothing to do with good luck. It is years of hard work ______ has made him what he is today.

A. why

B. when
C. which
D. that

深圳港位于广东省珠江三角洲南部，珠江入海口伶仃洋东岸，毗邻（）。是（）地区优良的天然港湾。