Final Answer:
This week's academic vocabulary word is "serene". Using a dictionary or online resource, look up the definition of the word. Then choose the option below that illustrates the appropriate definition serene: to be calm, clear, and untroubled. so the correct option is a Serene: to be calm, clear and untroubled.
Step-by-step explanation:
a. The correct definition of "serene" is to be calm, clear, and untroubled. Therefore, option a is the appropriate choice.
Option b is incorrect because it suggests becoming fixated or obsessed on a topic, which is not the meaning of "serene."
Option c is incorrect as it refers to turbulence during a flight at high altitudes, which is unrelated to the calm and untroubled nature of the word "serene."
Option d is also incorrect as it describes intense feelings of guilt or remorse, which is not synonymous with the peaceful and calm connotations of "serene."
In summary, option a accurately represents the definition of "serene" as calm and untroubled.