Select the most appropriate synonym of the given word.

Heyday

The correct answer is "Prime". 

Key Points

• The term "heyday" refers to the period of one's greatest success, prosperity, or vigor.
• It's commonly used to refer to the time when someone or something was most powerful or popular.
  • Example: "In his heyday, the athlete was virtually unbeatable."
• The term "prime" can refer to the period of greatest achievability or success, the peak of one's life or career. 
  • Example: "During the prime of his career, the musician released multiple chart-topping albums that solidified his place in the music industry."
• From the above explanation it is clear that both words are synonyms to each other. 

Therefore, the correct answer is "Option 3". 

Additional Information

• Yesteryears: This term generally refers to past times.
• Though it could suggest a similar concept to "heyday" in the sense of looking back at a previous time, "yesteryears" do not inherently convey the aspect of being in one’s prime or at a peak of power or success.
• Dreamy: This term is typically used to describe something that is serene, pleasing, or fantastic (like in a dream), or it is used to describe someone who is not focused on the present.
• Fateful: This term usually refers to something that has far-reaching and often disastrous consequences or implications.