Answer:
Option D, Competitive species
Step-by-step explanation:
A competitive species is one which being commercially fruitful is in high demand in consumable market.
Lobster being competitive , has high demand due to which it is cultivated/harvested in large amounts with in a short span of time. Due to such high demands , the species like lobster (as mentioned in this question) suffers from the issue of over harvesting and thus their average size reduces over time as they do not get enough time to mature.
Option D is correct.