Öğretmen: What did you learn about scientists in your research, Elif?
Elif: I learned that some scientists make discoveries by accident. For example, Alexander Fleming discovered penicillin when he noticed mould killing bacteria in his lab.
Öğretmen: That's a good example. Can you name another?
Elif: Yes, the microwave oven was invented after Percy Spencer noticed a chocolate bar melted in his pocket near a radar machine.
According to the conversation, what do both discoveries have in common?
A)They were made by the same scientist.
B)They happened by accident during other work.
C)They were both invented in the 20th century.
D)They both involved bacteria.