String the·o·ry
noun
a cosmological theory based on the existence of cosmic strings.
They has been very successful but they are very expensive to operate that is your answer I hope this helps
Answer:
A. Measurements are made with tools; observations are not
Explanation:
Measurement: <em>the assignment of numbers or codes according to prior-set rules. </em>
Observation: <em>data from an individual study subject or sampled unit.</em>
Measurement error: <em>differences between "true" answers and what appears on data collection instruments</em>
hope this helps
plz mark brainleist