Answer: Complete protein source.
Explanation:
Complete protein source can be defined as the food sources that contains each of the nine amino acids. It is the adequate amount of diet which is required by the body in order to meet the demand of the body.
Rice and beans are complementary proteins which are combined together in order to make a complementary proteins.
The bean and rice alone does not makes complementary diet so they are combined together to form a complementary diet which has all the 9 essential amino acids.
Single source complete protein are yogurt, cheese, milk, egg, red meat et cetera.
For some reason I have a little bit of doubt that this is related to your schoolwork, however this is important to learn to not do so by mistake. This would take a few minutes of inhaling fumes and is a very painful way to die. Even if it doesn't kill you, exposure can lead to brain damage and chemical burns. 5-10 minutes of non ventilated inhaling.
The correct answer would be #3.
Calcium rich food will be most beneficial to prevent osteoporosis. For eg, milk, cheese, cereal, soybean, spinach etc.
