Abroad body of evidence, subject to revisions, supported by different kinds of scientific investigations and often involving the contributions of scientists from different disciplines is necessary to develop
a. an inference
b. a theory
c. a fact
d. a prediction

b. a theory

Explanation:

A theory is said to be a well structured explanation of a result in particular field of study.  A theory tend to follow series of steps in an attempt to explain a result ;

Hypothesis : This is said to be a knowledgeable guess in the field of sciences.

Observation : The scientist engage in thorough study or observation of the experiment or facts he wants to establish.

Experiments : The scientist engage in series of experiments to back up his fact and observation.

A theory is propounded if it is testable . The theory must have passed through a series of scientific research to become an establish facts. It must pass numerous  scientific investigation and often involving contribution from well meaning scientist in that domain.  The theory must be simple , precise  and express-able so it can be repeated by other scientist.    This established fact should not contradict previous principles or theory but instead expand and agree with others.