The correct answer is 4 states for a minimal deterministic finite automaton (DFA) that accepts the language of all strings over {0, 1} containing neither the substring "00" nor the substring "11." The number of states in a DFA corresponds to the number of distinguishable states needed to recognize the language.
For this particular language, you need 4 states to distinguish between different substrings and ensure that the automaton recognizes the correct strings. Each state represents a different stage of reading the input and keeping track of whether the current substring contains "00" or "11."
If you draw a DFA with fewer than 4 states, it won't be able to distinguish between all possible strings in the language, and it will not be minimal. A minimal DFA is one that recognizes the language with the fewest possible states. In this case, a DFA with 4 states is the minimal DFA for the given language.