Answer:
Option B is correct.
Step-by-step explanation:
Option A:
[tex]y=-6x^3[/tex]
graph of this function is attached.
Maximum value does not exist for this function.
Option B:
[tex]y=-5x^4[/tex]
graph of this function is attached.
Maximum value does exist for this function.
Option C:
[tex]y=5x^6[/tex]
graph of this function is attached.
Maximum value does not exist for this function.
Option D:
[tex]y=6x^5[/tex]
graph of this function is attached.
Maximum value does not exist for this function.
Therefore, Option B is correct.
