Let's check each option:
a.
[tex]\begin{gathered} \frac{-1}{12}\cdot\frac{6}{7}=\frac{-1\cdot6}{12\cdot7}=\frac{6}{84} \\ \text{We can rewrite the expresion:} \\ \frac{6}{84}=\frac{6\cdot-1}{6\cdot14} \\ \text{Simplify the common term }\frac{6}{6}=1,\text{ Then} \\ =\frac{-1}{14} \end{gathered}[/tex]b.
[tex]\begin{gathered} \frac{-1}{12}\cdot\frac{-6}{7}=\frac{(-1)(-6)}{(12)(7)}=\frac{6}{84} \\ \text{We can rewrite the expresion:} \\ \frac{6\cdot1}{6\cdot14} \\ \text{Simplify the common term }\frac{6}{6}=1,\text{ then:} \\ =\frac{1}{14} \end{gathered}[/tex]c.
[tex]\begin{gathered} \frac{1}{12}\cdot\frac{6}{7}=\frac{1\cdot6}{84} \\ \text{We can rewrite as:} \\ =\frac{1\cdot6}{6\cdot14} \\ \text{Simplify the common term }\frac{6}{6}=1,\text{ then:} \\ =\frac{1}{14} \end{gathered}[/tex]d.
[tex]\begin{gathered} \frac{1}{12}\cdot\frac{-6}{7}=\frac{(1)(-6)}{84} \\ \text{We can rewrite as:} \\ =\frac{1\cdot-6}{6\cdot14} \\ \text{Simplify the common term }\frac{6}{6}=1,\text{ then:} \\ =\frac{-1}{14} \end{gathered}[/tex]Hence, the correct answers are options A and C.