Which of the following containers is a single-unit container intended for parenteral administration only?

The USP has classified containers as follows: a single-dose container is a single-unit container in- tended for parenteral use, a tight container protects the product from contamination, a single- unit container is designed to hold a quantity of drug product intended for administration as a single dose after the container is opened, and a unit-dose container is a single container intended for administration other than by the parenteral route as a single drug directly from the container.