First strong entity types are made to tables. So, we get two tables $M$ and $P$.
I assume $R1$ is $1:1$ or $1:n$ as that would minimize the number of tables as asked in question.
Now participation of $M$ in $R1$ is total (indicated by double arrow) meaning every entity of $M$ participate in $R1$. Since $R1$ is not having an attribute, we can simple add the primary key of $P$ to the table $M$ and add a foreign key reference to $M$. This handles $R1$ and we don't need an extra table. So, $M$ becomes ${M1, M2, M3, P1}$.
N here is a weak entity weakly related to $P$. So, we form a new table $N$, and includes the primary key of $P (P1)$ as foreign key reference. Now $(P1, N1)$ becomes the primary key of $N$.
Thus we get $3$ tables.
$M: {M1, M2, M3, P1}$ - $M1$ primary key, $P1$ references $P$
$P: {P1, P2} - P1$ primary key
$N: {P1, N1, N2} - (P1, N1)$ primary key, $P1$ references $P$.
So, answers is B.