A test which is administered at the end of a language course for remedial teaching is—

The correct answer is diagnostic test.

A diagnostic test is designed to identify specific strengths and weaknesses in a learner's knowledge or skills. In language teaching, when a course ends or during ongoing assessment, a diagnostic test helps educators pinpoint exact areas where students face difficulties so that effective remedial teaching can be planned and provided.

Let's look at why the other options are not correct:

• Placement test: Used prior to a course to determine the appropriate level or class for a student based on their initial proficiency.

• Achievement test: Used to measure how much a student has learned or mastered from the taught syllabus at the end of a unit or course.

• Memory test: Focuses primarily on rote recall of information rather than assessing specific linguistic gaps for remediation.