请教。不明白什么意思GWD2-Q21

Telomerase is an enzyme that is produced only in cells that are actively dividing.  For this reason it is generally absent from body tissues in adults.  Bone marrow is an exception to this rule, however, since even in adults, bone marrow cells continually divide to replace old blood cells.  Cancers are another exception, because their cells are rapidly dividing.

The information provided most strongly supports which of the following?

1. Telomerase is the only enzyme that is present in cancerous cells but absent from cells that are not actively dividing.
2. In children, the only body tissues from which telomerase is absent are those in which cells are not rapidly dividing.
3. The presence of telomerase in bone marrow is no indication of bone marrow cancer.
4. Cancer of the bone marrow develops more rapidly than cancer growing in any other kind of adult tissue.
5. The level of telomerase production is always higher in cancerous tissue than in noncancerous tissue.

这道题应该是什么意思呀？答案是A/C

答案是C

T出现在cells that are actively dividing， Bone marrow，Cancers这三种情况下，C在Bone marrow出现的时候不表示有Cancers，因为有可能是一种正常的存在。

A的only enzyme文中无从得知。

题目的意思就是

T是一种在孩子长身体（细胞活跃分裂期）的时候产生的酶，在通常情况下成年人不会有。有两种例外，一是在骨髓细胞中，因为就算是成人，骨髓细胞也会继续分裂替代老化血细胞；二就是癌症，癌症本身就是细胞快速（不正常）的分裂。