Explanation:

Let’s break down the question and the options:

- Section 50, Indian Evidence Act: Deals with the relevance of opinions regarding relationship, especially concerning proof of relationship (like marriage, etc.), but has a *proviso* stating that such opinion isn't relevant in prosecutions under a specified Section of the IPC.

- Proviso of Section 50: Clearly mentions it does not apply to prosecutions under Section 304-B, IPC (Dowry Death).

Let's look at your options:

- Option 1: Section 304-B, IPC

- Relates to Dowry Death.

- Specifically mentioned in the proviso to Section 50 of the Evidence Act.

- Correct Answer

- Option 2: Section 303-B, IPC

- There is no Section 303-B in the IPC.

- Option 3: Section 302-B, IPC

- There is no Section 302-B in the IPC.

- Option 4: Section 301-B, IPC

- There is no Section 301-B in the IPC.

So, the correct answer is Option 1: Section 304-B, IPC, as it's the only valid and relevant section mentioned.