3. Four candidates $A, B, C, D$ are participating in the student council election. It is known that candidate $D$ received more votes than candidate $B$, the sum of votes for candidates $A$ and $B$ exceeds the sum of votes for candidates $C$ and $D$, and the sum of votes for candidates $A$ and $C$ is equal to the sum of votes for candidates $B$ and $D$. Then the ranking of the four candidates from highest to lowest in terms of votes is ( ).
(A) $A, D, C, B$
(B) $D, B, A, C$
(C) $D, A, B, C$
(D) $A, D, B, C$
3. D.

As shown in Figure 4, represent using a circle.
Since the total votes for candidates $A$ and $C$ are equal to the total votes for candidates $B$ and $D$, draw a diameter to divide the circle into two halves, with the upper half for $B$ and $D$, and the lower half for $A$ and $C$.

Given that candidate $D$ received more votes than candidate $B$, the sector area for $D$ is larger than the sector area for $B$; since the total votes for candidates $A$ and $B$ exceed the total votes for candidates $C$ and $D$, the combined sector area for $A$ and $B$ is greater than the area of a semicircle.
Therefore, the ranking of the candidates by the number of votes from highest to lowest should be D.