Step 1: Identify the Author.
\textit{Being and Time} is a foundational existentialist philosophical text authored by Martin Heidegger. It is a significant work in 20th-century philosophy concerning the concept of being.
Step 2: Analyze the Options.
- 1. Beauvoir is incorrect; Simone de Beauvoir, though an existentialist, did not write \textit{Being and Time}. - 2. Sartre is incorrect; Jean-Paul Sartre, another existentialist, is not the author of this book. - 3. Heidegger is correct; he is indeed the author of \textit{Being and Time}. - 4. Husserl is incorrect; Edmund Husserl influenced Heidegger but did not author this work.
Step 3: Conclusion. The correct answer is 3. Heidegger.
Final Answer: \[ \boxed{\text{The correct answer is 3. Heidegger.}} \]