Answer:
option: A($70)
Explanation:
We are given Selling Price(S.P.) of the goods=$21
Let the cost price(C.P.) of the goods be denoted by 'x'.
Also we are given that the loss percentage is equal to the C.P.
i.e.




This means that x=70 or x=30
Hence from the options given we could say that the cost price of goods is $70.
Hence option A is correct.