XL solver question

[sandvenu]

Problem statement :

I have 3 plants with demand of 5000,3000 and 2000. I have 4 suppliers whose capacities are 5000,3000, 7000,5000 and 6000. I need help in writing a constraint in XLS solver such that only one supplier is selected for each plant :

Please let me know if you need any additional information

Thanks