参考答案

正确答案：A
解析：这是一道细节理解题。根据原文第三段前几句"The reason lies in the expectations of the researchers． They had been looking for the usual type of cave drawing of painting，which shows Up best under direct light，Consequently，they used powerful torches，shining them straight onto the rock face．”(研究者的先人为主之见是导致失败的原因。他们以为此次的图画与以往发现的洞穴画一样，用光直射就可以完美显现。因此，他们使用了强光手电筒，利用它们直射到石头表面。)可以知道，以往的做法此次是行不通的，所以选项A“Traditional way of viewing was employed．”(启用传统视图方法)是失败之源。故选A。