The scientific method cannot be used to study which of the following phenomena

Science cannot prove or refute the existence of God or any other supernatural entity.

The scientific method cannot be used to study the phenomena of  "the authenticity of UFO sightings".

Explanation:

The scientific method is an empirical method used mainly in the natural and social sciences n order to prove a theory. It consists of formulating a hypothesis and applying careful observation to the experimental data and behavior of the theory's agents and parts. After the observation, all the information and data is analyzed in order to prove, by logical reasoning and empirical methods, whether the theory is correct or not. The phenomena of "the authenticity of UFO sightings" is too broad and unreliable for someone to study it by using the scientific method, as the variables in it are not constant or controlled, and the term "authenticity" is too subjective to be defined scientifically.

the answer is "a.) well–developed vascular system."

explanation: