A 2.6.9-ac1 kernel would be
A.
an alpha kernel.
B.
someone’s patch to a stable kernel.
C.
a stable kernel.
D.
an unstable kernel.
E.
someone’s patch to an unstable kernel.
Explanation:
2.x is a stable kernel if x is an even number. Kernels are numbered like 2.6.37. (see www.kernel.org)
B.
someone’s patch to a stable kernel.