Given that d is the midpoint of ab and b is the midpoint of ac, which statement must be true? a: ad = 1/3 ac b: ac = 4db c: ab + dc = ac d: bk = kc

B: AC = 4DB

Step-by-step explanation:

Since B is the midpoint of AC, this means that AB≅BC.

Since D is the midpoint of AB, then AD≅DB.

This means that AD is 1/4 of the length of AC, since it is 1/2 of 1/2 of the length (1/2*1/2 = 1/4).  DB is the same length, since it is congruent to AD.

This means that AC = 4DB.