A)
Since we're dealing with an isoseles triangle you know that the bottom two angles are congruent (A&B).
Also you know that line CM creates a midpoint in line AB and also biscects angle C. There you have all three angles so D is out along with B. Now to Illiminate C we know that line CM is shared so that's one side, because line CM creates a mid point in line AB lines AM and BM are congruent so that's the second side and if we look at the triangle as one isoseles again we know that the two upper sides are congruent, that's the last side to illiminate C. Leaving us with A, the dont give us any measurements so you aren't able to look at the heights and lengths.
