Reason - goats would not be good to use as money, but coins would be ok:
In my opinion, I think that Coins would be preferable because it is measurable equivalent to a specific amount. A goat’s worth could either be underestimated or overestimated.
The coins are also easily transferable, they can be transferred and transported at any point of time but in the same situation, a goat can't be transferred or transformed at any point of time as the need arises.
This question is a simple example of the barter system, as the system requires other trader to have the commodity required by this seller, which is mostly unlikely, So currency / coins helps in making the trade a lot more easier . Thus, coins are better .