Final answer:
Determining a date for the arrival of the first humans in Japan is complicated due to lack of written records and reliance on varying archaeological evidence from a time predating recorded history. so, option C is the correct answer.
Step-by-step explanation:
The difficulty in determining a date for the arrival of the first humans in Japan lies in a combination of factors, but prominently due to a lack of written records. Without written accounts, historians and archaeologists rely primarily on archaeological evidence to understand the past. This evidence often comes from tools, remnants of settlements, or other cultural artifacts that can be challenging to date precisely.
The geographical isolation of Japan, after being severed from the Asian mainland, further complicates this issue since it limited interactions that could have provided additional context and artifacts for dating. Given that the first human habitations in Japan predate recorded history and are based almost entirely on archaeological finds, establishing an accurate timeline is problematic.