4.4 Let D be the diagraph with vertices V1, V2, V3, V4 corresponding to the following matrix M: 0 1 1 0 1 0 0 0 1 1 0 1 0 1 0 1 a) Sketch the diagraph D. [5] b) Determine whether D is strictly unilaterally connected, strongly connected or neither. Justify your answer. [2]