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The luminosity of a Seyfert galaxy nucleus varies in a time-scale of 6 days. What could be the largest possible size of the emitting region?

The luminosity of a Seyfert galaxy nucleus varies in a time-scale of 6 days. What could be the largest possible size of the emitting region?
Select one:
a.
5 pc
O b. 8.5×102 pc
○ c. 0.75 pc
рс
O d. 5×10-3 pc
рс

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