Explanation:
A cyclone is a large-scale weather system characterized by low pressure at its center and strong winds circulating around it. Cyclones can cause significant damage and loss of life, so it is important to issue warnings in advance to allow people to prepare and take necessary precautions.

Definition of First Stage Cyclone Warning:
The first stage cyclone warning is the initial alert issued by meteorological departments to inform the public and authorities about the potential development of a cyclone. It provides information about the possible track, intensity, and timing of the cyclone.

Advance Notice:
The advance notice given for a first stage cyclone warning is crucial for preparedness and emergency response. It allows people living in the affected areas to evacuate if necessary, secure their belongings, and take other precautionary measures.

Options:
a) 48 hrs advance
b) 72 hrs advance
c) 36 hrs advance
d) 12 hrs advance

Correct Answer: Option B - 72 hrs advance

Explanation of the Correct Answer:
The correct answer is option B - 72 hrs advance. This means that the first stage cyclone warning is issued 72 hours in advance before the expected arrival of the cyclone.

Reasoning behind the Correct Answer:
1. Option A - 48 hrs advance: This option suggests that the first stage cyclone warning is issued 48 hours in advance. However, this may not provide sufficient time for people to adequately prepare and take necessary precautions.

2. Option B - 72 hrs advance: This option suggests that the first stage cyclone warning is issued 72 hours in advance. This allows for a longer preparation period, giving people more time to evacuate if needed, secure their belongings, and make necessary arrangements.

3. Option C - 36 hrs advance: This option suggests that the first stage cyclone warning is issued 36 hours in advance. While this provides some advance notice, it may not be enough time for comprehensive preparations.

4. Option D - 12 hrs advance: This option suggests that the first stage cyclone warning is issued only 12 hours in advance. This would provide very little time for people to prepare and respond effectively to the cyclone threat.

Conclusion:
In conclusion, the correct answer is option B - 72 hrs advance. Issuing the first stage cyclone warning 72 hours in advance allows for sufficient time for people to prepare and take necessary precautions to mitigate the potential impact of the cyclone.

Correct answer is option'B'