Correct answer is:

a) KaTeX parse error: KaTeX doesn't work in quirks mode. chocolates

Explanation

We know,
KaTeX parse error: KaTeX doesn't work in quirks mode. day KaTeX parse error: KaTeX doesn't work in quirks mode. hours
And, KaTeX parse error: KaTeX doesn't work in quirks mode. week KaTeX parse error: KaTeX doesn't work in quirks mode. days
KaTeX parse error: KaTeX doesn't work in quirks mode. week KaTeX parse error: KaTeX doesn't work in quirks mode. hours
KaTeX parse error: KaTeX doesn't work in quirks mode. hours.
Now,
Every KaTeX parse error: KaTeX doesn't work in quirks mode. hours a chocolate factory produces KaTeX parse error: KaTeX doesn't work in quirks mode. chocolates
KaTeX parse error: KaTeX doesn't work in quirks mode. Every KaTeX parse error: KaTeX doesn't work in quirks mode. hours a chocolate factory produces KaTeX parse error: KaTeX doesn't work in quirks mode. chocolates
KaTeX parse error: KaTeX doesn't work in quirks mode. Every KaTeX parse error: KaTeX doesn't work in quirks mode. hours a chocolate factory produces KaTeX parse error: KaTeX doesn't work in quirks mode. chocolates
KaTeX parse error: KaTeX doesn't work in quirks mode. chocolates.
Ans: The end of a week a chocolate factory produces KaTeX parse error: KaTeX doesn't work in quirks mode. chocolates.