Explanation:
An earthquake is a natural disaster that can cause significant damage to buildings and infrastructure, as well as pose a threat to human life. During an earthquake, it is important to take appropriate actions to ensure personal safety.

Option A: Take elevator to go downstairs
Taking an elevator during an earthquake is not recommended. Elevators can malfunction or get stuck during an earthquake due to power outages or structural damage. This can put individuals at risk of being trapped in the elevator, which can be dangerous if there is a fire or other hazards. It is safer to use the stairs to evacuate a building during an earthquake.

Option B: Immediately come to an open ground
This option is the correct answer. During an earthquake, it is important to move to an open ground away from buildings, trees, and other structures that can pose a risk of falling or collapsing. Open spaces provide a safer environment and reduce the risk of being injured by falling debris.

Option C: Do not touch electrical wires or equipment
This option is a correct action to take during an earthquake. It is important to avoid touching electrical wires or equipment during an earthquake as they may be damaged or become live, posing a risk of electric shock. It is recommended to stay away from electrical sources and turn off the main power supply if it is safe to do so.

Option D: None of the above
This option is incorrect as option B (Immediately come to an open ground) is the correct action to take during an earthquake. Taking an elevator during an earthquake (option A) is not recommended, and it is important to avoid touching electrical wires or equipment (option C) to prevent the risk of electric shock.

In summary, during an earthquake, it is important to stay calm, move to an open ground away from buildings and structures, avoid touching electrical wires or equipment, and follow any additional safety guidelines provided by local authorities.