This is the type of question you should quickly destroy.
The structure of the argument is simple, and it is easy to see why the premise does not undeniably prove the conclusion.
Let's look at the argument structure first:
Premise: Mindt Chocolate's new candy bar is most clearly designed to compete with our most popular candy bar, famous for its distinct black and orange package.
Premise: The names of the two bars, which appear on the package, make them easily distinguishable. Saturn's bar is called Sniggers while ours is named Chuckles.
Conclusion: Mindt uses a similar package, which makes it likely that many consumers intending to buy our candy (Saturn's) bar will mistakenly buy Mindt's instead.
Lets look at the options:
A. Many popular candy bars are sold in packages of standard size -
Out of scope. The standard size of all candy bars doesn't matter. What concerns is the packaging (or black and orange packaging to be precise). Eliminate A.B. Sniggers weighs almost twice as much as does Chuckles. -
Again out of scope. Weight doesn't help us weaken the conclusion. Eliminate BC. Mindt is a relatively new company whereas Saturn was founded almost a century ago. -
Out of scope. Lifetime of a company doesn't weaken the conclusion. Eliminate C.D. Mindt's most popular product sells as much as does Saturn's most popular product. -
Out of scope. Popularity of a company doesn't weaken the conclusion. Eliminate D.E. Sniggers is most popular among young children who do not yet read. -
We are left with E only by now. This option clearly weakens the fact that to distinguish between two chocloates you need to read the wrappers. With the consumers being young children who can't read they'll go by packaging and may not differentiate between Mindt and Saturn. This your answer.