Given the task definition and input, reply with output. In this task, you need to answer the given multiple-choice question on geometry. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Problem: the side of a rhombus is 20 m and length of one of its diagonals is 16 m . the area of the rhombus is ?
Options: a ) 223.28 , b ) 293.28 , c ) 293.78 , d ) 291.28 , e ) 193.28
b