She was started on Dexamethasone 16mg daily. What is the single most likely cause of her weakness?

A 73 year old woman with skeletal and brain metastasis from breast cancer has worsening low back pain and blurring of vision. She had weakness of her legs and minimal knee and absent ankle tendon reflexes and a palpable bladder. Her power is 2/5 at the hoip, 3/5 at the knee and ankle with tenderness over 2nd lumbar vertebrae. there is reduced sensation in the perineum. She was started on Dexamethasone 16mg daily. What is the single most likely cause of her weakness?

A. Paraneoplastic neuropathy
B. Progression of brain tumor
C. Steroid induced myopathy
D. Spinal cord compression ANS
E. Prolapsed inter-vertebral disc at L2-L3