4 mat-weavers can weave 4 mats in 4 days. At the same rate, how many mats would be woven by 16 mat-weavers in 16 days?  Choose the most appropriate option
A) 25  B) 19  C) 39  D) 61  E) 64

Rationale: "let the required number of bottles be x . more weavers , more mats ( direct proportion ) more days , more mats ( direct proportion ) wavers 4 : 16 : : 4 : x days 4 : 16 4 * 4 * x = 16 * 16 * 4 x = ( 16 * 16 * 4 ) / ( 4 x 4 ) x = 64 . answer is e ."
Answer: E