Let's solve this problem by setting up an equation.

Let:
- \( x \) = number of pencils bought
- \( y \) = number of notebooks bought

We know:
- Each pencil costs \( N3.00 \), so the total cost for pencils is \( 3x \).
- Each notebook costs \( N5.00 \), so the total cost for notebooks is \( 5y \).
- The total amount spent is \( N25.00 \).

The equation is:
\[
3x + 5y = 25
\]

To find the number of pencils (\(x\)), we need to solve this equation with possible integer values of \(y\).

Case 1: \( y = 1 \)
\[
3x + 5(1) = 25 \implies 3x + 5 = 25 \implies 3x = 20
\]
\( x = \frac{20}{3} \) (Not an integer, so not possible)

Case 2: \( y = 2 \)
\[
3x + 5(2) = 25 \implies 3x + 10 = 25 \implies 3x = 15
\]
\( x = \frac{15}{3} = 5 \) (This is an integer, so it's possible)

Thus, \( x = 5 \).

Therefore, the number of pencils bought is B. 5.