The author took a moment to _________ his thoughts on paper, capturing the essence of the beautiful sunset.

• Set down
English Meaning:
- to write something down on paper in order to record it
​- to give something as a rule, principle, etc.
Bangla Meaning: 
- লিখে রাখা।
-  আরোপ করা।

Complete sentence: The author took a moment to set down his thoughts on paper, capturing the essence of the beautiful sunset.

• প্রশ্নে উল্লেখিত অপশন গুলোর মধ্যে -
• Set on
English Meaning: to attack somebody suddenly
Bangla Meaning: হঠাৎ আক্রমণ করা।

• Set out
English Meaning: to begin a journey
Bangla Meaning:  যাত্রা করা।

• Set apart
English Meaning: to make somebody/something different from or better than others.
Bangla Meaning: পৃথক করা

Source: Bangla Academy Dictionary and Oxford Learner's Dictionary.