For your first question regarding sources of probable cause, the option that is NOT typically considered a source of probable cause is:
c. Hearsay
Hearsay is generally not admissible as evidence in court, and while it can sometimes contribute to probable cause, it does not alone constitute probable cause.
For your second question regarding the interpretation of habeas corpus in the case of County of Riverside vs. McLaughlin (1991), the correct answer is:
c. 48 hours
In that case, the Supreme Court ruled that individuals arrested without a warrant must be brought before a judge within 48 hours.