"I get by with a little help from my friends" is a popular lyric(抒情诗) with age-old wisdom behind it. 【B1】______ people need people is something we have 【B2】______ understood, but more recent research has confirmed the relationship 【B3】______ good health and good social relationships. 【B4】______ infants, the lack of human interaction may 【B5】______ retard (阻滞) the development of intelligence. Adults who seek supportive social relationships find greater longevity(长寿) and have 【B6】______ chances of developing a disease.
Most of us 【B7】______ develop relationships to increase our life spans 【B8】______ to improve our minds and bodies. Such improvements are side 【B9】______ . Instead, most people seek relationships 【B10】______ others to feel love, gain companionship, or simply to have fun. Mutual interests can be a 【B11】______ for new relationships. A good 【B12】______ to find new friends is to get busy 【B13】______ the things you love to do. That way, you're 【B14】______ to meet more people who 【B15】______ a similar interest and a similar view of the world.
A good relationship helps you feel lovable and capable. It 【B16】______ as a support system, 【B17】______ you to develop your full potential 【B18】______ a person. One of the most 【B19】______ things you can do for friends is to help them develop their self-concept as they help you develop 【B20】______ .

A. Because
B. Which
C. That
D. Whether