Choose the closest paraphrased version after the following sentence or the italicized part.
The grouping of these explosives is one of the most highly classified aspects of the atomic bomb.（ ）
A、
The quality of the explosives matters a lot in classifying atomic bombs.
B、
These explosives play the most important role in making the atomic bomb.
C、
How to arrange these explosives is the top secret in making the atomic bomb.
D、
What characteristics of these explosives are used in making the atomic bomb is still unknown.
【正确答案】：C
【题目解析】：
句子释义：这些不同的炸药的排列是有关原子弹的最高机密之一。
C选项“怎样排列这些炸药是制造原子弹的最高机密”符合题意。