PLS HELP I MARK U AS BRAINLIST OR HOW EVER ITS CALLED

Find the sum of the following series. round to the nearest hundredth if necessary.

Which of the following statements is true? a. the irrational number system is not closed under multiplication, because the product of two irrational numbers is always a rational number. b. the irrational number system is not closed under multiplication, because the product of two irrational numbers is not always an irrational number. c. the irrational number system is closed under multiplication, because the product of two irrational numbers is always an irrational number. d. the irrational number system is closed under multiplication, because the product of two irrational numbers is always a rational numbers. reset submit

Find the circumference of a pizza with a diameter of 10 inches round to the nearest tenth