human
Question: Suppose that observations are available on the monthly bond prices of 100 companies for 5 years. What type of data are these?
A: Cross-sectional
B: Time-series
C: Panel
D: Qualitative
Please eliminate two incorrect options first, then think it step by step and choose the most proper one option.
gpt
--- Reasoning ---
1. Is the question multiple-choice question?
Yes

--- Answer ---
grounded