To answer this question, we need to understand the concept of current and the effects of electric shock on the human body.
When an electric current passes through the human body, it can cause harm depending on the magnitude of the current. Generally, currents greater than 10 milliamps can cause muscular contractions and pain, while currents greater than 100 milliamps can be fatal.
In this case, Jane accidentally grabs the positive terminal of her car's battery in one hand and the negative terminal in the other. The battery is rated for 100 amps, but it doesn't mean that the full 100 amps will flow through Jane's body.
The actual current that flows through a person's body depends on the resistance of the body. The human body has a relatively high resistance, typically around a few thousand ohms. According to Ohm's Law (V = I * R), the current flowing through the body will be determined by the voltage (12 volts) and the resistance (of the human body).
Given that the resistance of the human body is relatively high, the current flowing through Jane's body will be much lower than the maximum rating of the battery.
Therefore, in this scenario, the current flowing through Jane's body will be significantly less than 100 milliamps. As a result, she will experience a mild shock at most, but it will not be fatal. So, the correct answer is A) Nothing.