The number of possible monobromination products, including cis-trans isomers, of methylcyclopentane is: A) 2
B) 3
C) 4
D) 5
E) 6

D) 5

Explanation:

In this case, the "monobromination" is the addition of one "Br" to the molecule. With this in mind, we have to explore each option to put this "Br" atom:

1) (bromomethyl)cyclopentane = The Br atom is placed in carbon 6

2) 1-bromo-1-methylcyclopentane = The Br atom is placed in carbon 1

3) (1R,2R)-1-bromo-2-methylcyclopentane = The Br atom is placed in carbon 2 (with trans configuration)

4) (1R,2S)-1-bromo-2-methylcyclopentane = The Br atom is placed in carbon 2 (with cis configuration)

5) 1-bromo-3-methylcyclopentane = The Br atom is placed in carbon 3

See figure 1

I hope it helps!