Yuda. How long have you been an orphan?

Heru: For eight years now. My father died when I was a baby, and my other died eight years ago.

Yuda: Why don't you live with your grandparents?

Heru: Because they have passed away. My grandfather died even before I was born, and my grandmother died six years ago.

From the dialogue above, we know that Heru's father died when....

a. he moved to orphan house

b. he was a baby

C. he was eight years old

d. he was six years old