Answer: a passive; active
Step-by-step explanation:
When a person or institution is said to have a passive asset allocation strategy it means that they either trade the same assets over and over or apply the same weighting to the asset class every time. Stephen only trades medical-related stocks so is using passive allocation.
An active security selection strategy means that the person or institution constantly changes and trades the stocks in their portfolio much like Stephen does when he constantly trades stock. Stephen is therefore using an active security selection strategy.