Final answer:
Severe heart defects like tetralogy of Fallot and patent foramen ovale can result in "blue baby" syndrome, exhibiting cyanosis, which is a blue hue to the skin due to insufficient oxygen in the blood.
Step-by-step explanation:
Trouble with heart defects, such as severe septal defects including tetralogy of Fallot and patent foramen ovale, can lead to a condition colloquially known as "blue baby" syndrome. This condition is characterized by a distinctive blue or purple coloration of the skin, known as cyanosis, due to an insufficient supply of oxygenated blood. When considering the options provided in the question, the correct answer is a) Blue.