Answer:
Sample
Explanation:
Given that to estimate size of trout in a lake, an angler records the weight of 11 trout he catches over a weekend.
Hence it is implied that to assess the weight of trouts in general i.e. the whole population he draws a random sample of 11 trouts caught over a week end. He believes that this sample represents the whole population and hence some measured can be estimated from sample statistics.
Thus the data of 11 trouts taken is a sample here