I don't know what the example is, but taciturnity means quietness. So the answer is D.
Remedy means a treatment to cure diseases or injurious(in this case hearing problems)
Singed means to burn something(in this case her hair)
Quarrel mean to fight or argue with someone(in this case his bro)
Conclude means to end something or bring something to an end
Enormous means something huge or big or large in size or quantity
I will correct the mistakes in the sentences:
A. I thought I seen him in the yard.
Mistake! It should be:
A. I thought I saw him in the yard.
C. When had you saw him last?
Mistake! It should be:
C. When had/have you seen him last?
D. Mary sawed that man again yesterday.
Mistake! It should be:
D. Mary saw that man again yesterday.
So, options A, C and D have mistakes, but option D does not have a mistake in it!
Answer:
<em>C) People are more productive when they enjoy their work.</em>
