cgoose the odd one out and give reason

Answers
Answer:
1. hay fever
2. carbon dioxide
3. skin
4. ?
●hay fever because all the other given options are connected to allergies but hey fever is a type of fever
●carbondioxide because all the other things are related to our body like water we drink ,energy for doing any work and calcium is present in our bones but coming to carbondioxide it's a harmful gas which we release by taking oxygen in to our body
●teeth because all the other options are shown properly or can be seen properly but whereas teeth are inside the mouth and cant be seen properly until anyone open there mouth
●excretion because all others are the methods of filtration or absorbing or secreting but whereas coming to excretion its the waste present in our body and which we release it in the form of a motion or urine
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