Ounces and mg.
Oh Dear!!!! your English grammar is at fault. The question should read ' Which metric unit is the mass of an orange?'. NB 'Witch' is a female sorceress 'Which' is the question. To answer the question, an orange would be weighed in grams.
It is a customary unit.
The opposing systems are imperial and metric, not customary. But, meters are metric.
The pound is NOT a metric unit.
It can be more or less. An once (customary) is bigger than a gram (metric) but a pound (customary) is smaller than a kilogram (metric).
It is customary.
Metric.
Metric.
Metric
A "gran" is a German measurement, it is neither customary or metric. A "gram" is a metric unit.
customary
It is a customary unit.