Step-by-step Solution:

(a) \( x + y = y + x \): True. Addition in Boolean algebra is commutative.\[\] (b) \( x \cdot y = y \cdot x \): True. AND in Boolean algebra is commutative.\[\] (c) \( x \cdot x' = 1 \): False. In Boolean algebra, \( x \cdot x' = 0 \), because \( x' \) represents NOT \( x \).\[\] (d) \( x + x' = 1 \): True. In Boolean algebra, \( x + x' = 1 \) by the complement law. \[\] Correct Option: (c)