Final answer:
In William Bradford's narrative, he provides firsthand details on the mortality rates and hardships faced by the Pilgrims, including how many deaths occurred in the first few months.
Step-by-step explanation:
Among the options provided for what firsthand detail William Bradford includes in his narrative, the correct answer is B) The report about how many deaths occurred in the first few months. Bradford's account is valuable because it includes direct observations and experiences from the early settlement period, which might not have been as accurately conveyed through secondhand reports. Details such as the exact number of deaths suffered by the Pilgrims during their first winter at Plymouth give us direct insight into the stark mortality rates and hardships they faced, which is a type of detail that could be understated or overlooked by others not directly affected by these events.