Task: Question Answering
Input (English): Question: What is the main cause of functional urinary incontinence in the elderly? 
 Options:  <1> Detrusor instability. <2> Obstruction due to fecalomas. <3> Laxity of the muscles of the pelvic floor. <4> Environmental barriers. <5> Urinary retention induced by medication.
Output (English): 4