A consumer has $20 that he wants to spend on two goods: pens priced at $2 each, and pencils priced at $1 each. Which of the following correctly represents his budget constraint?

A) $20 = ($2/Quantity of pens) + ($1/Quantity of pencils)
B) $20 = ($2 × Quantity of pens) + ($1 × Quantity of pencils)
C) $20 = ($3/Quantity of pens + Quantity of pencils)
D) $20 = $3 × (Quantity of pens - Quantity of pencils)

B