I think the answer must be 4.
For E1,E2,E3 we will defiantly need one table each.
By putting primary key of E2 i,e G in E1's table we can specify the indentifing relationship R between them. Hence no need of table for R.
But For P we will need a different table in which we will put primary key of E3 i,e E and Primary key of E1 i,e C as foreign keys and the primary key of the table for P will be the combination of E and C i,e EC
Hence we need total 4 tables( for E1, E2 ,E3 and for P)