The synonym of the word "stringent" is-

Correct answer: rigorous.

Stringent (adjective)
- Bangla meaning: কঠোর; অবশ্য পালনীয়। .
- English meaning: marked by rigor, strictness, or severity, especially with regard to rule or standard.

Rigorous
- Bangla meaning: কঠোর; প্রচণ্ড।
- English meaning: manifesting, exercising, or favoring rigor: very strict.

Other options:

ক) Dry
- Bangla meaning: শুষ্ক; জলীয় বাষ্পহীন।
- English meaning: free or relatively free from a liquid and especially water.

গ) Strained
- Bangla meaning: অধিক চাপ, পেশীতে টান পড়া।
- English meaning: done or produced with excessive effort

ঘ) Shrill
- Bangla meaning: to utter or emit an acute piercing sound.
- English meaning: তীক্ষ্ণ; কর্ণবিদারী; কর্কশ।

Source:
1. Merriam-Webster dictionary.
2. Accessible Dictionary.
3. Cambridge Dictionary.