We've covered this in detail in earlier threads/posts
It's complicated ... but, basically, there is an embedded second option exercisable at 20c, and valid for 3 yrs, when you exercise the first option at 10c.
So, the fair value of ERHO is thus = price of ERH x 2 - 30c + time and volatility premium.
i.e. a heck of a lot more than where it's offered for sale now
