When including trend effects in exponential smoothing, how many smoothing constants are required?

Multiple choice question.

None

One $-$ alpha $(\backslash$alpha $)$

Two $-$ alpha $(\backslash$alpha $)$ and delta $(\backslash$delta $)$

Three $-$ alpha $(\backslash$alpha $),$ epsilon$(\backslash$epsi $),$ and delta $(\backslash$delta $)$