Which one among the following is not a good source of nutritional calcium?

1. Nutritional calcium is essential for bone health and various bodily functions. 2. Ragi (finger millet) is known to be a very good source of calcium compared to other cereals. 3. Skimmed milk is an excellent source of calcium (similar calcium content to whole milk, but less fat). 4. Eggs (particularly the yolk) contain some calcium, making them a moderate source. 5. Rice, especially polished white rice, is generally not a good source of nutritional calcium; its calcium content is quite low compared to the other options. 6. Therefore, Rice is the option that is not a good source.