choice
prompt "This is always invisible"
depends on n
config DUMMY
bool "DUMMY"
endchoice
choice
prompt "Choose A or B"
config A
bool "A"
config B
bool "B"
endchoice
config FOO
bool "FOO"
depends on A
choice
prompt "Choose X"
depends on FOO
config X
bool "X"
endchoice