A baby animal knows what to do after birth just from natural instinct. Human babies do not get taught how to breath or cry, they know to do so because they would die otherwise.
The economic implications have to do with agriculture. Look what happens when there is an outbreak of mad cow or hoof and mouth disease. Thousands of farmers lose their herds and are financially devastated. This also affects the consumer because the decrease in supply will drive up the costs. But, it could also have the opposite effect. If consumers no longer feel safe, then they will stop eating the particular food and the farmers will lose money.
The same is true with disease in plants. Tobacco mosaic virus can devastate crops, resulting in huge economic losses. On a grand scale, crop diseases can affect human history. Potato blight caused suffering and death in Ireland and resulted in massive migration. Many descendents from Irish folks in the U.S. wouldn't be here if it weren't for a crop disease.
D because it’s healthy for the baby to eat protein