A composite rod is formed by joining a glass-reinforced plastic rod and a nylon rod end to end, as shown. Both rods have the same cross-sectional area, and each rod has a length of $1.00\,\text{m}$. The Young modulus $E_p$ of the plastic is $40\,\text{GPa}$ and the Young modulus $E_n$ of the nylon is $2.0\,\text{GPa}$. The composite rod breaks once its total extension reaches $3.0\,\text{mm}$. What is the maximum tensile stress that can be applied to the composite rod before it breaks?
- A$2.9 \times 10^6\,\text{Pa}$
- B$5.7 \times 10^6\,\text{Pa}$
- C$2.9 \times 10^9\,\text{Pa}$
- D$5.7 \times 10^9\,\text{Pa}$