2. Until the 1500s, doctors thought diseases were caused spontaneously. Scientists began proposing that diseases were caused by seed- like entities that could be passed among people. After the invention of the
microscope, doctors came to know that many diseases were actually caused by microscopic living
organisms, like bacteria. What does this suggest about the nature of scientific knowledge?
a. Scientific knowledge should not be considered valid because it changes over time.
b. Technology has improved enough that scientific knowledge can stop changing.
C. New discoveries and evidence are more important than repeatable results.
d. Scientific knowledge changes over time based on evidence.