Sentence 1: Our fire alarm is the original one since the house was built. 
 Sentence 3: Every time someone takes a hot shower the alarm goes off 
 Sentence 4:  But whenever someone burns food it doesn't make a peep 
 Sentence 5:  I think there's something faulty with the fire alarm 
 Option 1: The house is now 25 years old. 
 Option 2: The house is only three years old, so it's in perfect condition.