Thisphenomenonstillhasmanyofthemwonderingtheirheads.

参考答案:

D

词语运用,scratch one’s head 表：认真地思索一个难题；例：This crisis has politicians scratching their heads and wondering what to do.(这场危机令政治家们苦思不得其解。）；本句意为：这一现象仍令他们苦思不得其解。因此D为答案。