[NeedHelp3]

I am trying to figure out...
Which compound has the fewest number of stereoisomers and which has the greatest number of stereoisomers?

A. 2-Bromo-3-chloro-4-hexen-1-ol

B. 2-Bromo-4-chloro-4-hexen-1-ol

C. 2-Bromo-5-chloro-4-hexen-1-ol

D. 2-Bromo-6-chloro-4-hexen-1-ol

E. 4-Bromo-5-chloro-4-hexen-1-ol

I am getting the same number of chiral centers for C and D (zero).  I don't think this is right   I'm also struggling with the double bond, does that automatically make the carbon achiral? 

[Schrödinger]

A carbon atom is chiral only if it is attached to 4 different groups. So, a double bond automatically makes both the carbons achiral.

And number of chiral centers for C and D is 1, not zero.

[sjb]

A carbon atom is chiral only if it is attached to 4 different groups. So, a double bond automatically makes both the carbons achiral.

And number of chiral centers for C and D is 1, not zero.

True, but in some definitions (E)- and (Z)-but-2-enes are stereoisomers, as the atoms are arranged differently in space but have the same connectivity. You need to be careful here.

[Schrödinger]

True, but in some definitions (E)- and (Z)-but-2-enes are stereoisomers, as the atoms are arranged differently in space but have the same connectivity. You need to be careful here.

Yes, indeed.

But I wasn't talking about that. I was answering the OP's question regarding whether a double bond will make the carbon atom achiral or not :

I am getting the same number of chiral centers for C and D (zero).  I don't think this is right   I'm also struggling with the double bond, does that automatically make the carbon achiral? 

I wasn't referring to the molecule's chirality/stereochemistry. As a matter of fact, all the compounds listed by the OP have double bonds that give atleast 2 different stereoisomers (E and Z). Again, I say atleast because I don't want to give away the exact number that arises due to the presence of chiral centers