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If Mark saved an average (arithmetic mean) of $80 per week for 3 consecutive weeks, how much did he save the second week ？（）

(1)The average amount that Mark saved per week for the first 2 weeks was $60.

(2)The amount that Mark saved the first week was the amount he saved the second week and the amount he saved the third Week.

A．条件(1)充分，但条件(2)不充分．

B．条件(2)充分，但条件(1)不充分．

C．条件(1)和(2)单独都不充分，但条件(1)和条件(2)联合起来充分．

D．条件(1)充分，条件(2)也充分．

E．条件(1)和条件(2)单独都不充分，条件(1)和条件(2)联合起来也不充分．