Question

what are hypotheses partially based on?
conclusions
facts
observations
future events

Explanation:

A hypothesis is an educated guess. It is formulated after observing something in the natural world. Conclusions come after testing a hypothesis. Facts are established truths, but a hypothesis is a tentative statement. Future events are unknown and not a basis for forming a hypothesis. Observations of phenomena in the natural world (like seeing how plants grow under certain conditions) lead to formulating a hypothesis (e.g., "plants grow taller in more sunlight").

Answer:

C. observations