usage of and brings out a subordinate clause - wrong in A and C
D - running in them - wrong
E - with a predisposition seems to refer back to cholesterol.

IMO B.

I think E should be the answer.

a) and their families develop a predisposition to cardiovascular disease [color=red]- a complete sentence [/color]

b) whose families have a predisposition to cardiovascular disease - [color=red]"whose" refers to cholestrol
[/color]
c) and a predisposition to cardiovascular disease runs in the family [color=red]- a complete sentence[/color]

d) whose families have a predisposition to cardiovascular disease running in them [color=red]- "whose" refers to cholestrol [/color]

e) with a predisposition to cardiovascular disease running in their family [color=darkblue]-Parallelism "with ... with ......."[/color]

ranjeet75 wrote: b) whose families have a predisposition to cardiovascular disease - "whose" refers to cholestrol

whose here depends on what follows the pronoun to refer to the proper antecedent. Whose cannot refer to cholesterol as its followed by families referring to senior citizens.

e) with a predisposition to cardiovascular disease running in their family -Parallelism "with ... with ......."

with ... with ... - this doesn't give clear meaning. the second with seems to refer back to cholesterol. Or there should be a comma to connect the two but even that looks awkward. B seems way better in meaning.

Experts believe that senior citizens with higher than average cholesterol with a predisposition to cardiovascular disease running in their family are more likely to die at an age below that of their life expectancy.

IMO: B, because of parallel issues.

What is the OA?

Thanks.

None of the options actually look good.

Some expert please help.

Thanks.