Final answer:
The most common metric for the size of a product is the number of lines of code.
Step-by-step explanation:
The most common metric for the size of a product is the number of lines of code.
Lines of code (LOC) is a metric that signifies the number of lines of code written in a software program. It is often used to measure the complexity and size of a software product.
Other metrics like number of functions, number of variables, and number of classes can also be used to gauge the size of a product, but the number of lines of code is the most commonly used metric.