Nagihan created embroidery on a fabric in a single row using beads and sequins. In one part of this embroidery, she used 4 beads, and in the others, she used 5 beads to create motifs, and placed one sequin between each pair of adjacent motifs.
Nagihan started the embroidery with a motif and ended it with a motif, creating 56 motifs using a total of 300 beads and sequins.
Accordingly, how many motifs did Nagihan create using 5 beads?
A) 15
B) 21
C) 28
D) 36
E) 40