$8.$ Which of the following sentences contains at least one gramatical error?

a$.$ A training assessmant identifies competencies that are needed on the job.

b$.$ Competencies are the knowledge, skills, and behaviors needed for individuals to succeed on the job.

c$.$ Training should be focused on the core competencies needed for successful job performance.

d$.$ Employees should take advantage of training opportunities since they are vital to career advancement.