Go through the following statements
(i) The secodnary oocyte undergoes meiosis II which proceeds only till metaphase until a sperm enters it.
(ii) Ovulation occurs about 36-38 hours after the start of LH surge at midcycle.
(iii) In humans, it takes about 74 hours to form a mature sperm from a primitive germ cells.
(iv). About 70% of the human ejaculate is contributed by bulbourethral glands
Which of these are correct?

Options

A. (i) & (iii)
B. (ii) & (iii)
C. (i) & (ii)
D. all are correct

Explanation

To determine which statements are correct, let's analyze each one step by step.

### Step 1: Analyze Statement (i)
**Statement:** The secondary oocyte undergoes meiosis II which proceeds only till metaphase until a sperm enters it.

**Analysis:** This statement is correct. The secondary oocyte does indeed undergo meiosis II but is arrested at metaphase II until fertilization occurs. When a sperm enters, it triggers the completion of meiosis II.

### Step 2: Analyze Statement (ii)
**Statement:** Ovulation occurs about 36-38 hours after the start of LH surge at midcycle.

**Analysis:** This statement is also correct. The luteinizing hormone (LH) surge is a key trigger for ovulation, which typically occurs about 36-38 hours after the surge begins.

### Step 3: Analyze Statement (iii)
**Statement:** In humans, it takes about 74 hours to form a mature sperm from a primitive germ cell.

**Analysis:** This statement is incorrect. The correct duration for the maturation of sperm from primitive germ cells is approximately 74 days, not hours.

### Step 4: Analyze Statement (iv)
**Statement:** About 70% of the human ejaculate is contributed by bulbourethral glands.

**Analysis:** This statement is also incorrect. The majority of the fluid in human ejaculate is contributed by the seminal vesicles, not the bulbourethral glands.

### Conclusion
Based on the analysis:
- **Correct Statements:** (i) and (ii)
- **Incorrect Statements:** (iii) and (iv)

### Final Answer
The correct statements are (i) and (ii).

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