Institution: জাতীয় কবি কাজী নজরুল ইসলাম বিশ্ববিদ্যালয় (JKKNIU) Exam: ঙ ইউনিট || জাতীয় কবি কাজী নজরুল ইসলাম বিশ্ববিদ্যালয় || 2012
Topic: Sentence (বাক্য), Subject: English Grammar (ইংরেজি গ্রামার)

Best Answer Explained in Below-:

The question asks for the noun form of the verb "lose." In English, verbs can be transformed into corresponding nouns, and understanding this transformation is key to identifying the correct answer among the options provided.

1. **Option A: Lost** - "Lost" is the past tense and past participle form of "lose." While it describes something that has been lost, it does not function as a noun.

2. **Option B: Loss** - "Loss" is indeed the noun form derived from the verb "lose." It refers to the state of no longer having something, often associated with a lack of possession or the process of losing something. This makes it the most appropriate choice.

3. **Option C: Losses** - While "losses" is a plural form of "loss," it still fundamentally represents the concept of loss, making it less suitable since the question seeks a singular noun form.

4. **Option D: Losing** - "Losing" is the gerund or present participle form of "lose." It describes the action of losing rather than identifying a concrete noun.

In summary, "loss" is the direct noun form of the verb "lose," making "B: Loss" the correct answer. It encapsulates the concept of losing something, whereas the other options either represent different grammatical forms or pluralization.