Answer
a. Satisfiable
b. Satisfiable
c. Satisfiable
Work Step by Step
a) if p is true and q is false ($\neg q $ is true), then the compound proposition is true and thus the compound proposition is satisfiable.
b) if p is true, q is false ($\neg q $ is true) and s is false ($\neg s$ is true), then the compound proposition is true and thus the compound proposition is satisfiable.
c) If p is false ($\neg p$ is true), q is true, r is false ($\neg r $ is true) and s is false ($\neg s$ is true), then the compound proposition is true and thus the compound proposition is satisfiable.