Which of the Following Describes the Function of the H $\lambda$

Which of the following describes the function of the H protein,sometimes known as the tape measure,during assembly of the $\lambda$ virion?

A) It controls the amount of viral DNA packaged into the head.
B) It controls the length of the tail.
C) It controls the size of the head.
D) It cleaves the viral DNA and produces the cos sites.
E) It attaches the tail to the head.