The policies of Richard Nixon and Lyndon Johnson were similar in that b) both understood that voting rights needed federal protection.
Both presidents recognized the importance of ensuring that all citizens had the right to vote and that federal intervention was necessary to protect these rights, particularly in the context of the civil rights movement. Johnson was instrumental in passing the Voting Rights Act of 1965, while Nixon continued to support measures to protect voting rights during his presidency.
The other options, while they may reflect some views held by either president, do not represent a shared understanding in the same way that voting rights do.