A 45-year-old woman has had mild pain over her left lower back that radiates to her left lower limb, for the past 2 years. After lifting a heavy case of soft drinks, the pain intensified and she was admitted. Radiographic examination revealed disk herniation between vertebral levels L4 and L5. Which nerve was most likely affected by the disk herniation?
A. L1.
B. L2.
C. L3.
D. L4.
E. L5.