Why Were the Huguenots Deemed a Threat by the French

Why were the Huguenots deemed a threat by the French monarchy until the reign of Henry IV?

A) They were English spies sent by Queen Elizabeth who attempted to assassinate French kings.
B) Conversion of French nobles to Calvinism meant that members of the ruling class supported the cause, thus creating an opportunity for resistance to the government.
C) They were Dutch and Flemish rebels who opposed both Spanish and French intrusion in their homelands.
D) They were members of a rival noble family, seeking revenge against the Valois dynasty.
E) They were an elite force of Spanish soldiers, who took orders directly from Philip II.