Answer: A
In general, large molecular weight compounds equilibrate slowly between the vascular space and the interstitium. Thus, calculations of the rate of removal by TPE can be simplified to first order kinetics.
First Order Kinetics : Elimination is directly proportional to its plasma concerntration. First order implies that no matter how much concentration the macromolecules is they will be eliminated by 50% in its first half- life, i.e. time-dependent. Concentration decrease is exponential on a graph.
Zero Order Elimination: This form of elimination is independent of time or concentration. Concentration decrease is linear on a graph.
Reference
1. UpToDate
2. Information about zero and first order kinetics here