在密实砂土地基中进行地下连续墙的开槽施工，地下水与地面齐平，砂土的饱和重度γsat=21kN/m3，内摩擦角=35°，内聚力C=0，采用水下泥浆护壁施工，槽内的泥浆与地面齐平，形成一层不透水的泥皮，为了使泥浆压力能平衡地基砂土的主动土压力，使槽壁维持稳定，泥浆比重至少应达到（）选项的值。 （）

A.1.1

B.1.3

C.1.5

D.1.7

Since we are social beings, the quality of our lives depends in large measure on our interpersonal relationships. One strength of the human conditions is our possibility to give and receive support from one another under stressful conditions. Social support makes up of the exchange of resources among people based on their interpersonal ties. Those of us with p support systems appear better able to deal with major life changes and daily problems. People with p social ties live longer and have better health than those without such ties. Studies over types of illnesses, from depression to heart disease, show that the presence of social support helps people defend themselves against illness, and the absence of such support makes poor health more likely.
Social support cushions stress in a number of ways. Firstly, friends, relatives and co-workers may let us know that they value us. Our self-respect is strengthened when we feel accepted by others in spite of our faults and difficulties. Secondly, other people often provide us with informational support. They help us to define and understand our problems and find solutions to them. Thirdly, we typically find social companionship supportive. Taking part in free-time activities with others helps us to meet our social needs while at the same time distracting us from our worries and troubles. Finally, other people may give us instrumental support—money aid, material resources, and needed services—that reduces stress by helping us resolve and deal with our problems.

What is the subject discussed in the text

A. Interpersonal relationships.
B. Kinds of social support.
C. Ways to deal with stress.
D. Effects of stressful conditions.