调节体内钙磷平衡的主要因素之一，下列哪个答案是正确的()

A．甲状腺激素

B．生长激素

C．心钠素

D．甲状旁腺激素

E．醛固酮

Teams are required for most engineering projects. Although some small hardware or software products can be developed by individuals, the scale and complexity of modern systems is such, and the demand for short schedules so great, that it is no longer (1) for one person to do most engineering jobs. Systems development is a team (2) ,and the effectiveness of the team largely determines the (3) of the engineering. Development teams often behave much like baseball or basketball teams. Even though they may have multiple specialties, all the members work toward (4)．However, on systems maintenance and enhancement teams, the engineers often work relatively independently, much like wrestling and track teams. A team is (5) just a group of people who happen to work together. Teamwork takes practice and it involves special skills. Teams require common processes; they need agreed-upon goals; and they need effective guidance and leadership. The methods for guiding and leading such teams are well known, but they are not obvious.

空白（4）处应选择（）

A.multipleobjectives

B.differentobjectives

C.asingleobjective

D.independentobjectives