Final answer:
A spider web requires a small stress to deform due to its low elastic modulus, and this elasticity is crucial as it prevents the web from breaking when prey is caught, making the web an efficient trapping mechanism.
Step-by-step explanation:
To answer whether a large or small stress is required to deform a spider web, and why elasticity is important for a spider web, we must understand the relation between stress and strain in materials, as explained by the theory of elasticity. Spider webs have a relatively low elastic modulus, indicating that they are easily deformed when stress is applied, which implies that a small stress would lead to noticeable deformation. This is important as the elasticity allows the web to absorb the kinetic energy of prey hitting the web without breaking, making it an effective means for trapping insects.
The correct answer to the question is b) Small stress; elasticity prevents breakage.