Answer:
a) subsistence farming
Explanation:
The primary economic activities are the ones where the raw materials are produced, gathered, or extracted. This puts the likes of the farming and mining for example into the category of primary economic activity. The primary economic activities are supplying the means needed for the secondary economic activities to be able to produce manufactured goods.
The subsistence farming is a good example of primary economic activity. This type of farming is performed in a primitive manner. The people do the work on the fields manually, and the mechanization is either absent or almost absent in the work. The majority of the production, if not all, is used for feeding of the people that work on the fields, and it is only small amounts that might go for sale or exchange.
