Answer:
Plausible
Step-by-step explanation:
Regarding context of the given sentence, the alibi was supported by other reports, so it had potential to be truthful.
Thinking about this analyzation, let's look at the definition of each of these words.
Typical: Having or showing characteristics expected or associated with a particular thing.
Doubtful: Having an uncertain feeling
Plausible: Something seeming reasonable or probable
Given the definitions of the words as well as the context necessary to choose one, the most likely option is the third choice: plausible.