A technician has only two resistance coils. By using them singly, in series or in parallel, he is able to obtain the resistance of 3, 4, 12 and 16 $\mathrm{\Omega }$. What are the resistances of the two coils?

• A

  $6 \mathrm{\Omega } \mathrm{and} 10 \mathrm{\Omega }$

• B

  $4 \mathrm{\Omega } \mathrm{and} 12 \mathrm{\Omega }$

• C

  $7 \mathrm{\Omega } \mathrm{and} 9 \mathrm{\Omega }$

• D

  $4 \mathrm{\Omega } \mathrm{and} 16 \mathrm{\Omega }$