To access an internet site, users must select all unit squares containing car parts from the photograph divided into 9 unit squares below and click the confirm button.
Eda, who wants to access this site, randomly selected four different unit squares from this photograph and clicked the confirm button.
Accordingly, what is the probability that Eda can access this site?
A) $\frac{1}{15}$
B) $\frac{1}{36}$
C) $\frac{1}{56}$
D) $\frac{1}{84}$
E) $\frac{1}{126}$