Please help me with my assignment and it needs explanation

This data supplied by the cabbage growers union report for 2007: 80% of cabbages collected were heavy (over 0.5 kg), 10% of cabbages were green, 60% were red and 50% were big (having a diameter of over 10 cm). Which of the following statements must be false? Why?

a. All red cabbages weren't big

b. 30% of red cabbages were big

c. There were no cabbages that were both green and big

d. Half of the cabbages were small