The Golgi apparatus, sometimes called the Golgi body or Golgi complex, plays a critical role in the processing and packaging of proteins and lipids following their synthesis in the endoplasmic reticulum. It also has a role in the formation of glycoproteins and glycolipids. So, among the given statements : (A) It is the important site of formation of glycoprotein and glycolipids - This statement is correct. (B) It produces cellular energy in the form of ATP - This statement is incorrect. The mitochondria, not the Golgi apparatus, are responsible for the production of ATP. (C) It modifies the protein synthesized by ribosomes on ER - This statement is correct. The Golgi apparatus modifies and packages proteins received from the ER. (D) It facilitates the transport of ions - This statement is not generally correct. Ion transport is primarily facilitated by the plasma membrane and ion channels. (E) It provides mechanical support - This statement is incorrect. While the Golgi apparatus does help maintain cellular structure to a degree, its main role is in processing and packaging substances, not providing mechanical support. So the most appropriate answer from the options given would be Option B : (A) and (C) only.