Answer:
2nd option
Explanation:
As you can see in the graph
there are both inclusive and exclusive points
for d(x) = 1 if 1 <= x < 4 here 1 inclusive and 4 exclusive
= 2 if 4 <= x < 6
= 3.5 if 6 <= x < 11
= 5 if 11 <= x < 13
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