What is the minimum size of the IPv6 packet header?

What is the minimum size of the IPv6 packet header?

• 40 octets
• 36 octets
• 32 octets
• 48 octets             

EXPLANATION

The IPv6 packet header has a minimum size of 40 octets. Options are implemented as extensions. This provides the opportunity to extend the protocol in the future without affecting the core packet structure.
RFC 2460; Internet Protocol, Version 6 (IPv6) Specification, S. Deering, R. Hinden (December 1998)
https://en.wikipedia.org/wiki/IPv6