a)
\(B=\left\{a\right\}\), \(C=\left\{b\right\}\), \(D=\left\{c\right\}\)
\(B\subset A\), \(C\subset A\), \(D\subset A\)
b)
\(E=\left\{a,b\right\}\), \(F=\left\{b,c\right\}\), \(G=\left\{c,a\right\}\)
\(E\subset A\), \(F\subset A\), \(G\subset A\)