The diagram below illustrates the biological pathways involved in the body's acute and chronic responses to stress: the Sympathomedullary Pathway (SAM) and the Hypothalamic-Pituitary-Adrenal (HPA) axis.

For each numbered box (1, 2, 3, and 4), select the correct letter corresponding to the component from the list of options below.
List of Options:
Practise AQA A Level Psychology Stress with exam-style questions for A Level Psychology. 100 questions covering Physiology of stress, Role of stress in illness, Sources of stress, Measuring stress, Individual differences in stress, and Managing and coping with stress, matched to the AQA A Level Psychology (7182) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.