Solve this for my confirmation

S1 : I teach algorithms and maths.
S2 : My professor teaches maths,
electronics and computer
science.
S3 : I have a student of maths.
S4 : Algorithm is a part of
computer science.
S5 : Maths students know computer
science.
What would be the chromatic
number of a graph, vertices of which
are the actors/entities that are
involved in the sentences S1 to S5
and edges-to represent the
associations/relationships amongst
the entities/actors as expressed in the
sentences S1 to S5 above ?
(A) 2
(B) 3
(C) 4
(D) None of these