There are twenty amino acids that take part in protein synthesis. These amino acids act as precursor for all protein molecules and are known as essential amino acids. Plants can synthesize all twenty amino acids from simple precursors, while animals can make only twelve amino acids. Animals obtain remaining eight amino acids by eating plants.
The correct answer is the first option - Plants can synthesize all twenty amino acids. Humans must eat plants or animals to obtain twenty of these amino acids. We cannot just create these amino acids on our own the way plants can - we get them from the food we eat, which includes both animals and plants, not just one of them. This is the main difference between animals and plants when it comes to amino acids.
