Most reasonable answer is the swallowable camera one. mris and cat scans were invented in the 70s and the rest of the answers are around the 1800s or before.
Before assessing the two given cases, an assumption needs to be made about the digestion of the two types of food items, corn and beef. Let us assume that both get digested by expending same amount of energy by the human body. Let the amount of energy at producer level be an arbitrary X.
Case 1: Corn to human:
Since corn is at the producer level, it will have X amount of energy. The transfer of energy from corn to human will take place with a loss of 90% energy at the producer level. Hence the humans will receive 10% of X amount of energy.
Case 2: Corn to cow to human:
Since corn has X amount of energy, only 10% will pass to the next level, i.e. cow. So cow has 10% of X. Cow transfers only 10% of the energy that it has. Hence humans receive only 10% of 10% of X amount of energy.
It can be seen that humans receive more energy in case 1 than case 2. Hence we can say that it is more efficient for humans to feed on corn.
In the stomach, food undergoes chemical and mechanical digestion. Peristaltic contractions (mechanical digestion) churn the bolus, which mixes with strong digestive juices that the stomach lining cells secrete (chemical digestion). As food travels from your mouth into your digestive system, it's broken down by digestive enzymes that turn it into smaller nutrients that your body can easily absorb. This breakdown is known as chemical digestion.
The deer population would drastically be reduced with the slower rate of reproduction and predators that would kill more deer than can reproduce. The environment would likely also have a reduced population of predators for deer, since the food source is reduced.
