UKMLA PLAB AMC USMLE Prometric MCQ

Question:
A 40yr old man working in a chemical factory dealing with nitrates presented with generalized headache, dizziness and palpitations work. But as the week progressed in a day or two he recovered.
This phenomena is likely to be secondary to

a) Munchausen's Syndrome
b) Malingering
c) vasodilatation
d) Tachyphylaxis
e) Migraine