Dallas Unearths What He Thinks May Be a Gem While

Dallas unearths what he thinks may be a gem while he is working up a garden spot.He takes it to the local jeweler,who says he isn't sure until it is cleaned and polished,but he thinks it may be a semiprecious gem worth about $150.The jeweler offers to buy it,and Dallas is thrilled to sell for that price.If the jeweler later finds that the gem was really a precious gem worth ten times what he paid for it:

A) Dallas may rescind the contract of sale because of a mutual mistake.
B) Dallas may rescind the contract of sale because of a unilateral mistake.
C) the jeweler must contact Dallas to rescind the contract of sale or face fraud charges.
D) Dallas may not rescind the contract of sale. He knew there was uncertainty about the value of the exchange and accepted the risk.