Answer:a
Step-by-step explanation:
We have to lift the load two loads up one story, so energy required is
let m be the mass of each load and h is the height of each story
Energy
![E_1=2* m* g* \h](https://img.qammunity.org/2021/formulas/physics/college/dzik23d8c1h3iqm952o90ccyn6n409v5u9.png)
![E_1=2mgh](https://img.qammunity.org/2021/formulas/physics/college/poj0k35r6b2u2xznvfjdzvnjyifwjysifk.png)
Here energy gained is the potential energy which depends upon the datum(floor).
For lifting one load up one story
Energy required
![E_2=mgh](https://img.qammunity.org/2021/formulas/physics/college/v2aycsuotcsua2013zkbmzu6jhst017mg5.png)
thus
is half of
![E_1](https://img.qammunity.org/2021/formulas/physics/college/kvehacn22w5d8obc5c7qetqkoj634ujdwa.png)
So option a is correct