All over the world, more and more ocean freights are carried out with containers. This trend will continue because containerized shipment offers so many advantages. Among them are:1.EconomyOverall transportation costs can be reduced by the container shipment. In the case of general cargo of 10,000 tons, it takes 48 hours to load and unload. But for the container ship of 35,000tons, only 6-8 hours are needed. 2. SafetyTne cargo can be handled in any weather and is efficiently protected from theft and damage, because it is completely enclosed.3. Large scaleContainer ship has become giant, from 10,000 tons in 1970 to 100,000 tons now. It continues to grow bigger and bigger.There are two kinds of containers, 20'and 40', mostly adopted. 20'container is called TEU,Twenty-foot Equivalent Unit, and standard container. One 40'container equals two 20's.Containers are used in ocean, railway and highway transportation. In recent years, many container terminals have been established. The continental bridge transport is introduced to load containers by trains. The road transportation follows this tendency, and the tractors can pull the container at the speed of 100 km per hour on the highway.Questions:1. What is containerization shipment?
选项：

A:
A: To load goods in container;
B:
B: Container is the only choice for transportation;
C:
C: Containerized transportation;
D:
D: Container ship, container train and container truck