Answer: C) Effective duration

Implied MBS models are most closely associated with effective duration because they reflect how MBS cash flows and prices change when rates change, including the effect of embedded prepayment behavior.

Why the others are not as good:

• Macaulay duration assumes fixed cash flows.
• Modified duration also assumes fixed cash flows and is less suitable for option-like securities.
• Convexity is a curvature measure, not the best description of the model itself.

Effective duration is the best match because it is designed for instruments with changing cash flows, such as MBS.