Final answer:
The force of one Newton is both 'A' and 'C'.
Step-by-step explanation:
The force of one Newton is both 'A' and 'C'. Option 'A' states that one Newton is the force of gravity on a 1kg body, which is correct. Option 'C' states that one Newton gives a 1kg body an acceleration of 1 m/s², which is also correct.