What type of education follows the completion of a bachelor's degree?

The correct answer is graduate school, as it specifically refers to advanced levels of education pursued after obtaining a bachelor's degree. Graduate school typically includes master's and doctoral programs, which focus on specialized knowledge and skills in a particular field. This level of education often involves a deeper exploration of subjects and may require research or practical application, preparing students for professional careers or academic positions.

The other options are related to education but do not directly follow a bachelor's degree in the same way graduate school does. Vocational training usually provides specific skill sets for a trade or profession and may not require a bachelor's degree. Undergraduate studies refer to the educational phase where an individual works towards their bachelor's degree, and continuing education encompasses any educational activities that adults pursue after formal schooling, which may or may not be linked to advanced degree programs. Therefore, graduate school is distinguished as the next academic step after obtaining a bachelor's degree.