Final answer:
A conclusion based on incomplete information is known as a b) conjecture, referring to a statement made without all the necessary facts, indicating uncertainty and potential for error.
Step-by-step explanation:
An opinion or conclusion formed on the basis of incomplete information is typically referred to as a conjecture or a conjectural statement(option b).
This implies that the conclusion has been reached without access to all the necessary facts and is therefore uncertain. In critical thinking, a hypothesis can serve as a tentative explanation of observations that acts as a guide for gathering and checking information. However, hypotheses and conjectures are also subject to error, especially if based on inadequate evidence, leading to potential fallacies such as hasty generalizations or unwarranted assumptions. It is important to approach such conclusions with epistemic humility, acknowledging that more information may be necessary to form a sound judgment.