What is the effort force (input) in this picture from the levers lab? a) moving the fulcrum toward the clay block b) using the clay block c) moving the fulcrum toward the spring scale d) pulling down on the spring circle

The load is attached to the spring balance and fulcrum is kept at point B.

The support given to the load is done by the effort, which is done at point D using the clay block. If you remove the clay block, the spring balance at point A will fall down.

Hence, the effort force (input) in this picture from the levers lab is done using the clay block.

So, the option (B) Using the clay block is correct.

Effort is at point B

If we look at the picture there are several points. Point A shows the load attached and then point D is the force which is been applied by the string. It can also be considered as tension in the string. Effort is the point B. An input force or effort is applied, resulting in moving or applying an output force to a load. In a first-class lever the fulcrum is located at some point between the effort and resistance forces.

no sign of dia of fuel cell