[yolo!]

I believe my answers are:
a.   NO
b.   YES
c.   YES
d.   YES
e.   YES

Though i am not 100% confident that i am totally right on d. and e. especially. If someone could give me their thoughts that would be great! thank you 

[discodermolide]

What is the definition of optical activity?

[yolo!]

I know that optical isomers are nonsuperimposable mirror images....

[discodermolide]

OK, which of these compounds fulfil that definition? Remember that another criteria is that in the case of a tetrahedral carbon there must be 4 different substituents.

[yolo!]

Okay so b. And d. are not superimposable so they fit the definition. C. has 4 different substituents thus it falls under what you said. So What Is yes to b, c, and d?

[discodermolide]

Compounds b and c are the only optically active compounds in that list.
Compound d does not fit the criteria neither does compound e.

[yolo!]

I see it now just wrote it out! thank you very much for your help discodermolide:)