How many number of faces does a square-based pyramid have? What is the length of the marking pen?

A square-based pyramid has one square base.

It has 4 triangular faces that rise from the sides of the square base and meet at a single apex.
Adding the base, the total number of faces is $1 \text{ (base)} + 4 \text{ (triangular sides)} = 5 \text{ faces}$.

The calculated number of faces is 5, which matches option D.

The student's answer is ✅ Correct.
The correct option is D. Five.

The ruler starts at 0 cm. The left end of the marking pen aligns with the 0 cm mark on the ruler.

The right end of the marking pen aligns with the 10 cm mark on the ruler.

The length of the pen is the difference between the end mark and the start mark: $10 \text{ cm} - 0 \text{ cm} = 10 \text{ cm}$.

The calculated length is 10 cm, which matches option B.

The correct option is B. 10 cm.