Answer:
D. 0.44mg/kg
Step-by-step explanation:
Great question, first we need to find how many mg was given to the horse. Since 2 ml of dosage was given to the horse we can calculate
⇔ 
So, 200mg was given to a 1000 lb horse. Now we have to convert 1000 lbs into kg.

Now that we have the amount of kg we can calculate how many mg/kg like so,

So we can now see that the equivalent dose is 0.44mg/kg
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