The question pertains to the five laws of library science, proposed by S.R. Ranganathan, which are key principles in the field of library and information science. These laws are intended to guide the operations and management within libraries.

The second law states, "Every reader his/her book," which can be interpreted as "Know your community and its needs" in the context of a library. This law emphasizes that libraries should cater to the specific needs and preferences of their community or patrons. Essentially, it advises libraries to be aware of and responsive to the diverse needs of their users, providing access to materials and resources that align with their interests and requirements.

Now, let's analyze why the second law aligns with the given rephrasing:

• First Law: "Books are for use" - This focuses on the accessibility and usability of books, ensuring that library materials are available to users.
• Second Law: "Every reader his/her book" - This aligns with "Know your community and its needs" because it underscores the importance of serving the distinct needs and desires of the community.
• Third Law: "Every book its reader" - This emphasizes the distribution of books, ensuring that every book finds a reader, which is different from understanding community needs.
• Fourth Law: "Save the time of the reader" - This focuses on efficiency in satisfying the user's needs, not directly about knowing the community's needs.

Hence, the correct answer is the Second Law, which aligns with "Know your community and its needs."