Final answer:
According to the 1-year calendar model based on the Big Bang theory, the solar system formed in 'c. Days', around September 10 of the cosmic year. On this scale, the age of the solar system corresponds to about 4.5 billion years ago.
Step-by-step explanation:
Using the 1-year calendar model based on the Big Bang theory, if the Big Bang occurred at the very start of January 1, and the current time is the very end of December 31, the formation of our solar system would be represented as having occurred around September 10. Therefore, the correct answer to the question is 'c. Days' on the 1-year calendar model scale.
It is important to note that in actuality, the solar system formed about 4.5 billion years ago, which we know by the radiometric dating of rocks and other material in our solar system. These dating methods measure the decay of radioactive isotopes and have been pivotal in determining the age of the Earth, Moon, and other celestial bodies.