Final answer:
Vitamin A toxicity, or hypervitaminosis A, can cause a range of health issues including an enlarged liver, birth defects, and reduced bone density; hence, all the listed options are correct.
Step-by-step explanation:
Effects of Vitamin A Toxicity
Vitamin A toxicity, also known as hypervitaminosis A, can lead to several health issues due to an excessive build-up of vitamin A in the body. Some significant effects can include an enlarged liver, which may occur as the liver stores excess vitamin A and struggles to metabolize it, leading to hepatomegaly. Additionally, birth defects can result if a pregnant woman has excessive vitamin A levels, as it can interfere with fetal development. Lastly, reduced bone density is a known result of vitamin A toxicity due to its impact on bone metabolism. Therefore, the correct answer to the student's question is D. All of the above.