21. Many household accidents could have been prevented, but accidents seem to make news headlines every day. While accidents can happen anytime or anywhere, parents with young children can prevent accidents at home by taking a few steps.
      First, set your water heater correctly: To avoid burns from hot water, make sure your water heater’s temperature is set below 120° Fahrenheit, or set to “low”. Anything above that temperature can cause a child serious burns within seconds.
      Second, beware of candles: Statistics show that the small candle flames cause approximately 15,000 home fires a year. If you have young children and pets, stop using candles or be sure to blow them out before leaving a room.
      Third, recognize danger signals: It is important to pay attention to signs of danger from electrical appliances. If the wiring in your home does not function normally, you need to update it. Potential warning signs that might require an electrician’s inspection include wavering（摇晃的）TV pictures or computer screens, flickering（闪烁的）lights and shocks from appliances.
     It is impossible to prevent all accidents, so it is necessary to create a fire escape plan. In addition to having a smoke alarm on every floor of your home, draw a simple floor plan of your home. On it, mark two exits from every room, including windows and an outside family assembly point, such as a drive way or parking lot.(10分)

21.1  The possible target readers of this passage are ______.(2分)
A. grandparents
B. parents
C. grandparents with young children
D. parents with small kids