Which expression is a difference of cubes?

Answer:
Option 4 is correct.
Step-by-step explanation:
Given the following options
we have to choose the difference of cubes.
Option 1:
[tex]9w^{33}-y^{12}[/tex]
[tex]9(w^{11})^{3}-(y^4)^3[/tex]
which is not the difference of cubes
Option 2:
[tex]18p^{15}-q^{21}[/tex]
[tex]18(p^5)^3-(q^7)^3[/tex]
which is not the difference of cubes
Option 3:
[tex]36a^{22}-b^{16}[/tex]
[tex](6a^{11})^2-(b^8)^2[/tex]
which is the difference of square
Option 4:
[tex]64c^{15}-a^{27}[/tex]
[tex](4c^5)^3-(a^9)^3[/tex]
which is the difference of cubes.