Answer: The correct answer is the rock.
Step-by-step explanation:
Weight is defined as the force acting on an object due to the gravity. It is measured in Newtons.
The formula used to calculate weight of an object is given as:
......(1)
where,
W = weight of an object
m = mass of an object
g = acceleration due to gravity =

For the given objects:
Mass of book = 1.1 kg
Putting values in equation 1,we get:

Weight of the book is 10.78 N
Mass of rock = 2.3 kg
Putting values in equation 1,we get:

Weight of the rock is 22.5 N
Mass of box = 4.5 kg
Putting values in equation 1,we get:

Weight of the box is 44.1 N
Hence, the correct answer is the rock.