Ounces are typically used to measure liquid, so I would discourage choosing the top two. And, hopefully you know by now that an orange does not weigh 8 pounds.
(b) 8 ounces (best precision for likely weight of an orange)
Step-by-step explanation:
The most precision is obtained by using the smallest unit of measure. On this list, the smallest unit of measure is a tenth of an ounce. That is, the measure 0.8 ounces has the most precision.
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It is unlikely that the weight of one orange will be 0.8 ounces. The smallest unit used in a measurement likely to correspond to the weight of an orange is 1 ounce, used in the measurement 8 ounces. That measurement has better precision than 0.8 pounds, because 0.1 pounds corresponds to 1.6 ounces.