14. Let \( A=\{\phi,\{\phi\},\{\phi,\{\phi\}\}\} \), where \( \phi \) is a null set, then
(a) \( \phi \subseteq A, \phi \in A,\{\phi\} \in A,\{\phi\} \subseteq A \)
(b) \( \phi \in A \) but \( \phi \not \subset A \)
(c) \( \{\phi\} \in A \) but \( \{\phi\} \not \subset A \)
(d) \( A \) is a null set