According to Article 14 of the Provisions on Safeguarding Lawyers' Practice Rights according to Law, defense lawyers can consult, extract and copy the case files from the date when the people's procuratorate examines and prosecutes the case, except for the discussion records of the procuratorial committee of the people's procuratorate, the collegial panel of the people's court and the judicial committee and other materials that cannot be made public according to law. It can be seen that the statement of option A is wrong, in line with the meaning of the question and the correct answer.
According to Article 36 of the Criminal Procedure Law, defense lawyers can provide legal assistance to criminal suspects during investigation; Acting as an agent for complaints and accusations; Apply for changing compulsory measures; Ask the investigation organ about the crimes and cases suspected by the criminal suspect, and put forward opinions. It can be seen that in the investigation stage, the defense (only lawyers) have no right to investigate and collect evidence, and statement B is also wrong, but it conforms to the meaning of the question and is the correct answer. According to the provisions of Article 47 of the Criminal Procedure Law, defenders and agents ad litem have the right to lodge complaints or charges against acts of public security organs, people's procuratorates, people's courts and their staff members that hinder them from exercising their litigation rights according to law. It can be seen that c is right, but it does not meet the meaning of the question. According to the provisions of Article 9 of the Regulations on Six Organs, if a defender thinks that a suspected crime needs to be filed for investigation, "it shall be reported to the investigation organ at the next higher level of the investigation organ where the defender undertakes the case to designate other investigation organs for investigation, or the investigation organ at the next higher level shall file a case for investigation. The investigation organ at a lower level of the investigation organ that shall not appoint a defender to undertake the case shall file a case for investigation. " Therefore, D is wrongly expressed, which is in line with the meaning of the question and is the correct answer.