Which of these should be the FIRST sentence after rearrangement?

After reading all five sentences thoroughly, we can say that B is the first sentence as it introduces the topic of the passage. A, B and D form a group. B talks about how lung cancer has no symptoms during the initial stages of it. Sentence A further gives the reason why such is the case with lung cancer. D further adds that how in later stages, the symptoms do occur. C and E form a pair as E states that cancer can be diagnosed after running some tests and C describes that, on further testing, the type of cancer can also be identified. Rearranging sentences in the order of BADEC will make a coherent paragraph. So, the first sentence after rearrangement should be B.