human growth hormone

[heymayank08]

The human growth hormone, made by the pituitary gland, is secreted during sleep in higher concentrations than when awake.
(A) during sleep in higher concentrations than when awake
(B) when sleeping in higher concentrations than waking hours
(C) in higher concentrations during sleeping than waking
(D) in higher concentrations during sleep than during waking hours
(E) in higher concentrations when asleep than when awake

[spoiler]OA: D[/spoiler]

pls explain :B

[sam2304]

Relative pronouns like 'when' needs a noun to modify it.

A/B - Usage of when is wrong.
C - during sleep is the right usage
E - Similar to A/B, Who is asleep ? we need the noun here to make use of when. 'When people are awake' - This structure is right here people is the noun, but in the actual sentence it is missing and it seems the harmone is asleep if we were to link with a noun and that is wrong.

IMO D.

[GmatKiss]

Down to D/E and D seems awkward with "during waking"

IMO: Hard to choose between D/E

[dwilliams]

Wow, that is surprising. You can take a look here https://goodhgh.com/ to understand HGH better.