Which of the Following Presents an Example of an Additive $\quad\quad$

Multiple Choice

Which of the following presents an example of an additive design?

A) OOOO $\quad\quad$ XOXOXOXOXO
B) $\text { XOXO \quad XOXOXOXOXO } \quad OOOO$
C) $\text { XOXO } \quad OOOOOOOOOO$
D) $\text { OOOO ~~XOXOXOXOXO~~~ OOOO }$