In Theory, the Decision in the Case of Jackson V

In theory, the decision in the case of Jackson v.Indiana (1972) stopped which practice?

A) judges' refusal to allow mental health professionals to testify regarding the defendant's competence
B) defense attorney's refusal to inform the court of incompetency on the part of the defendant
C) having the defendant confined in a mental institution for extended periods of time
D) attempts by defendants to claim incompetence to avoid being tried for their crimes