Answer: C) SSS
The tickmarks are visual indicators telling that the segments are the same length.
The single tickmark segments RM and DE are the same length. The double tickmark segments RE and MD are the same length. There isn't enough information to be able to say if RM = MD is true or not.
The third set of sides that are the same length are EM and EM. It is possible to use a segment twice. In reality we can break up the figure to get two triangles. We can say that EM = EM by the reflexive property.
We have three pairs of congruent sides, so we end up using the SSS (side side side) congruence theorem.