I believe it is current. An ammeter is a measuring instrument used to measure the current in a circuit. Electric currents are measured in amperes (A), hence the name. Instruments used to measure smaller currents, milliampere or microampere range, are designated as milliammeters or microammeters.
I believe that it is A. If you remember in lesson 03.03 it gave multiple examples of things that support the continental drift theory. One of them was fossils of the same organisms found in different continents.
