A

Step 1: Define the lengths of the rods and the materials. Let \( L_c = 0.30 \) m (length of the copper rod) and \( L_s = 1.00 - L_c = 0.70 \) m (length of the second rod).

Step 2: Calculate the total change in length due to temperature change. Given the total change in length of the composite rod at \( 125º C \) is \( \Delta L = 1.91 \) mm = 0.00191 m.

Step 3: The change in length of each rod due to temperature expansion can be expressed as follows:
For copper rod: \( \Delta L_c = L_c \cdot \alpha_c \cdot \Delta T \)
For second rod: \( \Delta L_s = L_s \cdot \alpha_s \cdot \Delta T \)
where \( \alpha_c = 1.7 \times 10^{-5} /ºC \) and \( \Delta T = 125 - 25 = 100º C \).

Step 4: Substitute the values for the copper rod:
\( \Delta L_c = 0.30 \cdot 1.7 \times 10^{-5} \cdot 100 \)
Calculating \( \Delta L_c \):
\( \Delta L_c = 0.30 \cdot 1.7 \times 10^{-5} \cdot 100 = 0.00051 \) m = 0.51 mm

Step 5: Since the composite rod does not expand, it implies that the change in lengths are equal:
\( \Delta L_c + \Delta L_s = \Delta L \)
Therefore, \( 0.51 + \Delta L_s = 0.00191 \)
Which implies \( \Delta L_s = 0.00191 - 0.00051 = 0.00140 \) m = 1.40 mm.

Step 6: Calculate the coefficient of linear expansion for the second rod:
Rearranging gives: \( \alpha_s = \frac{\Delta L_s}{L_s \cdot \Delta T} \)
\( \alpha_s = \frac{0.00140}{0.70 \cdot 100} = \frac{0.00140}{70} \approx 2\times10^{-5}/ºC \)

Step 7: Calculate the stress in the copper rod:
Copper's expansion produces stress on the second rod proportional to Young's modulus:
\( Y_c = \frac{F}{A} \) relationship shows stress and expansion relationship: \( \frac{F}{A} = \frac{E_c \cdot \Delta L_c}{L_c} = E_c \cdot \alpha_c \cdot \Delta T \)
Therefore, using the relationship:
\( Y_s = \frac{E_c \cdot \Delta L_c }{L_c} = \frac{1.3 \times 10^{11} \cdot 0.51 \times 10^{-3}}{0.30} \)
Gives \( Y_s \approx 2.2 \times 10^{11} N/m^2.

Final Results:
1. Coefficient of Linear Expansion of the second rod \( \alpha_s \approx 2.0 \times 10^{-5}/ºC \)
2. Young's Modulus of the second rod \( Y_s \approx 2.2 \times 10^{11} N/m^2 \)
Hence, the identified values yield the solutions sought.