To determine the correct sequence of the sentences to form a coherent paragraph, let's analyze the context and logical flow of each sentence:
4. It started with a lump on Cathy Perkins’ index finger.
This sentence introduces the initial condition or starting point of the narrative.
2. The viola player didn’t know what it was; nor did her GP.
This follows logically as the next step, where the lump's ambiguity and the GP’s uncertainty are highlighted.
1. The eventual diagnosis was skin cancer and after treatment all seemed well.
This sentence provides resolution to the initial problem, stating the diagnosis and temporary resolution.
3. Then a routine scan showed it had come back and spread to her lungs.
This concludes the narrative with an unexpected twist, highlighting the recurrence and escalation of the condition.
Thus, the coherent sequence is: 4, 2, 1, 3.
The correct answer is 4213.