21) E

The question gives you the types of levers. You just need to understand which one applies to the action of moving load up and which lever is used to move the load down.

Imagine yourself doing a bicep curl in the gym!

You have the weight (load) in your hand which acts downwards due to gravity. Using your elbow (fulcrum) and the biceps (the arm muscles which applies the effort), you move the load up.

So, the load (whose weight acts downwards) which is on the left moves up, effort is in the middle and the fulcrum which is on the right moves up. This is shown by lever 3.

For the downward action, load is on your hand (left). Your fulcrum is in the middle. Your effort is to the right. This corresponds to lever 5.

You may be asking: Why is the fulcrum now in the middle? Position your arm as shown in the question. The bicep is in front of your elbow whilst your triceps are behind your elbow. Something like this:



Moving up action requires effort from your biceps whilst moving down action requires effort from your triceps. This is why the fulcrum is to right when moving up whilst it is in the middle when moving down.