The Octal number to be given alogn with chmod command to make a file readable, writable and executable to the owner, readable and executable to group and others is:

Answer: Option B

In Unix, file permissions are represented by three digits in octal form. Each digit corresponds to a set of permissions: the first digit for the owner, the second for the group, and the third for others. The permissions are represented by adding up the values for read (4), write (2), and execute (1).

For the owner to have read, write, and execute permissions (7 = 4 + 2 + 1).
For the group and others to have read and execute permissions (5 = 4 + 1).

So, the octal number to be given along with the chmod command to achieve these permissions is 755.