Final answer:
D) Diligence is a critical key to success in trading as it involves continuous learning and improvement. Being diligent allows traders to stay updated with market trends and make better decisions.
Step-by-step explanation:
A critical key to success in trading is D) Diligence - for continuous learning.
Diligence refers to the effort and dedication invested in continuously improving one's knowledge and skills in the trading market.
By being diligent, traders can stay updated with market trends, strategies, and new developments, which can ultimately lead to better decision-making and improved trading performance.