Consider a compound with the formula HOX. As the electronegativity of
atoms that could be substituted for X increases, the tendency of this
compound to behave as a base:
a. decreases
b. increases
c. remains the same
d. increases, then decreases.

From Table 8-1 on page 307, we see that the alkali metals have the
lowest electronegativities.  "These metals are the most reactive
known, and never occur naturally in the metallic state."  "All their
compounds are ionic, even the hydrides."  Page 324

In order to be a base, the compound with the oxygen and hydrogen atoms
must be ionic so that a hydroxide ion is formed.

Page 325 notes that the alkaline earth metals "...are more
electronegative than are the alkali metals; nevertheless all their
compounds, with the exception of some beryllium compounds, are ionic."

The electronegativities to continue to increase as one traverses the
periodic table of elements from left to right.  Therefore, the
tendency of the compound to behave as a base decreases (A).

All references are from Chemical Principles, fourth edition,
Dickerson, Gray, Darensbourg, Darensbourg, The Benjamin/Cummings
Publishing Company, Inc., 1984

Sincerely,

Wonko