Rate my bff. Pretty or ugly?

Which of the following is a way the operating system prevents unknown or unauthorized users from accessing the system?

The kurt vonnegut commencement speech, the neiman-marcus chocolate chip cookie recipe, and the get-well emails to the dying boy are examples of select one: a. social engineering b. hoax emails c. email viruses d. worms

Asequential circuit contains a register of four flip-flops. initially a binary number n (0000 ≤ n ≤ 1100) is stored in the flip-flops. after a single clock pulse is applied to the circuit, the register should contain n + 0011. in other words, the function of the sequential circuit is to add 3 to the contents of a 4-bit register. design and implement this circuit using j-k flip-flops.