I want to know the answer to the following question:
Upon what is Portuguese agriculture based?
All the background I'm provided with is that "However, the sector also includes larger scale intensive farming export-oriented agrobusinesses backed by companies (like Grupo RAR's Vitacress, Sovena, Lactogal, Vale da Rosa, Companhia das Lezírias and Valouro).". Is that enough to answer the question?