Giúp em được ko ạ. Thật sự em cần rất gấp ạ

UNIT 2 EX 7: Choose the word among A, B, C or D that best fits the blank space in the following passage. Dating people online has become an extremely popular custom that has developed as more and more people have figured out the (1). of using the Internet as a way of finding love. Peop ...