In designing a stair, the product of going (in cm) and the rise (in cm) should be equal to

In designing a stair, the product of going (in cm) and the rise (in cm

1.	In designing a stair, the product of going (in cm) and the rise (in cm) should be equal to
A.	300
B.	350
C.	400
D.	450
Answer» D.