Lead Toxicity clinical case.

A 6-year-old boy is brought to the physician by his mother because of "sleepiness:' she says that he has been so tired lately that he cannot even play with friends after school. Physical examination shows pale skin and mucous membranes. Laboratory studies show a decreased hemoglobin and hematocrit. Basophilic stippling is seen on a peripheral blood smear. Which of the following is the most likely diagnosis?

A. Arsenic poisoning

B. Carbon monoxide poisoning

C. Cyanide poisoning

D. Lead poisoning

E. Mercury poisoning