An investment of d dollars at k percent simple annual interest yields $500 over a 2 year period. In terms of d, what dollar amount invested at the same rate will yield $2,000 over a 4 year period? Select the correct option:
A) 2d	B) (3d)/4	C) (4d)/3	D) (3d)/2	E) (8d)/3
500 dollars in 2 years means 250 dollars in 1 year.   To get 2000 dollars' it will take 8 years.   To get 2000 in 4 years, we need 8/4= 
<gadget id="calculator">8/4</gadget>
<output>2</output>
2 times money. 2dnswer is 2d
<result>A</result>
An investment of d dollars at k percent simple annual interest yields $500 over a 2 year period. In terms of d, what dollar amount invested at the same rate will yield $2,000 over a 4 year period?