THE ANSWER IS the last one.
less then amount of energy
Of these options, it's often observation that is most likely to result in an inaccurate prediction, since objectivity plays a role. It's helpful to have more than one person observe at once.
1. Testing only one variable
A controlled variable means its the one that stays the same. In a controlled experiment, it means there is only one manipulated, (changed) variable.
One of the most intelligent invertebrate animal is the octopus. These animals belong to the cephalopod class of molluscs. These animals demonstrate relatively complex reasoning especially when capturing prey. They also demonstrate their intelligence by their communicating skills and some even show signs of learning.