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: if the height of a triangle is decreased by 40 % , land its base is increased by 40 % , what will be the effect on its area ?
Options: ['a ) no change', 'b ) 16 % increase', 'c ) 8 % decrease', 'd ) 16 % decrease', 'e ) none of thes']
d