there are four springs stretched by the same mass. spring a stretches 25 cm. spring b stretches 10 cm…

Brief Explanations:

According to Hooke's Law (F = kx) (where (F) is the force, (k) is the spring constant, and (x) is the extension). When the force (F) (due to the same mass, so (F = mg) is constant) is the same, the spring constant (k=\frac{F}{x}). A weaker spring has a smaller spring constant (k). Since (k) is inversely proportional to (x) (for constant (F)), the spring with the largest extension (x) has the smallest (k) (is the weakest). Among the given extensions ((x_A = 25\space cm), (x_B=10\space cm), (x_C = 100\space cm), (x_D = 1\space cm)), spring C has the largest extension.

Answer:

C. Spring C