Determine Whether the Given Formula Is a Logical Truth of M

determine whether the given formula is a logical truth of M or not. If it is not a logical truth, select a false valuation.
-(∃x) (Cx • Dx) $\lor$ (∃x) (Cx • ∼Dx)

A) Logical truth
B) Not a logical truth. False valuation in a domain of 1 member, in which:
Ca: True Da: False
C) Not a logical truth. False valuation in a domain of 1 member, in which: Ca: False Da: False
D) Not a logical truth. False valuation in a domain of 2 members, in which: Ca: True Da: True
Cb: True Db: False
E) Not a logical truth. False valuation in a domain of 2 members, in which: Ca: True Da: False
Cb: True Db: True