Eventually become

F (100) = f (f (f ... f (2015))) can enter the above piecewise function. This can be counted as ***384 F.

Then observe the trend:

F(20 15)=20 12 A layer of F has been removed. - 1

F(20 12)=2009 Remove a layer of F. -2.

F(2009)=f(f(20 14)) plus a layer of F.-1

F (2014) = 2011A layer of F has been removed. -2

F (2011) = f (f (2016)) plus a layer of F.-1

F(20 16)=20 13 A layer of F has been removed. -2

F(20 13)=20 10 Remove a layer of F. -3.

F(20 10)=f(f(20 15)) plus a layer of F. -2.

F(20 15)=20 12 enters the cycle.

You can see. After removing the two layers of f, the independent variable is still 20 15. But pay attention to the critical value of -3.

So we can know that the original f (100) =1... = f (f (2015)) = f (2012) = 2009.

If I do it, choose B.

I'm glad to answer your question. I hope I can help you. The basic education team wishes you progress in your study!

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