A companys market share went from 50 to 40 percent of the total market. Of the following choices, which two statements about the company's market shares are true?

• a.)

  There was a 25% decrease in market shares.

• b.)

  Market shares dropped by 20 percentage points.

• c.)

  There was a 10% decrease in market shares.

• d.)

  Market shares dropped by 25 percentage points.

• e.)

  Market shares dropped by 10 percentage points.

• f.)

  There was a 20% decrease in market shares.