Final answer:
The highest MA that can be obtained by a system of two pulleys is 4 (c).
Step-by-step explanation:
The mechanical advantage (MA) of a pulley system depends on the number of cables attached to the load. Each cable exerts a force in the same direction, so they add up to produce a total force that is an integral multiple of the input force.
In the given examples, a system with two cables attached to the load has an MA of approximately 2. A system with three cables has an MA of approximately 3. And a system with four cables has an MA of approximately 4.
Based on this information, the highest MA that can be obtained by a system of two pulleys is 4 (c).