MSRA-0864

A mother is referred to a paediatric gynaecologist with her 12-year-old daughter. Her daughter is extremely short for her age, is deaf in both ears and has shown no signs of pubertal development. On examination, the clinician notes neck webbing, a high arched palate and low-set ears. He suspects that the child may have Turner syndrome.
Which of the following chromosomal abnormalities best describes Turner syndrome?