题目内容：
Research on Child Psychology After the 1971 earthquake in Southern California, a group of researchers decided to (______1) a study of psychological effects of the quake on children who had experienced it. In carefully formulating the problems to be (______2) , the scientists stated their hypothesis that the children's dream would be quake-related but decreasingly so as time passeD． "Quake related" was (______3) in precise psychological terms. After studying the (______4) used by researchers who had (______5) fire-related dreams, they designed their (______6) . Data was (______7) over a period of two years, the time span which the researchers felt would be sufficient to (______8) their hypothesis. Early in 1973 they began a rigid (______9) of their data, though they had (______10) some tentative conclusion in the course of the two years. As part of the (______11) of the data, they (______12) the values for a graph of elapsed time versus quake related dreams. In a preliminary report of their (______13) given in a paper presented at a conference on child psychology held in late 1973, the researchers summarized the results they obtaineD．Following that, they began to prepare a lengthy report for publication. In that paper, they (______14) the developments of the research, (______15) the choice of subjects, and demonstrate the evidence which confirms their hypothesis. Finally, they recommend future research studies which may eventually help psychologists find ways to lessen the psychological impact of natural disasters such as earthquakes on both adults and children.请选择（1）处的最佳答案．
A．conduct B．buy
C．work
D．do
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