The first most obvious thing to note is when naming transitional metals, you have to state its charge with roman numerals (except for 1 if I remember correctly). For example, Iron (lll), iron has a charge of 3.
The answer is b.
Hope that helps :)
However many ounces you have, just multiply that by 28.34952. The answer to that is the conversion. so 5 ounces is 141.7476. Proof below.
It will only be valuable if proved correct so it's D