Sentence Correction

ardz24 wrote:Bumblebees live in colonies of several hundred that often have many queens as well as a large number of workers.

(A) of several hundred that often have many queens as well as
(B) of several hundred, often with many of them being queens as well as having
(C) having several hundred, and often many of them are queens as well as
(D) that have several hundred of them, often with many queens as well as
(E) with several hundred that often have many queens as well as having

OA: A

What's wrong with options B and D? Can any experts help?

B: Bumblebees live in colonies, often with many of them
Here, the referent for them is unclear.
If them = bumblebees, the following meaning is conveyed
Bumblebees live...often with many of bumblebees
If them = colonies, the following meaning is conveyed:
Bumblebees live in colonies, often with many of the colonies
The conveyed meanings in red are nonsensical.
Eliminate B.

SINGULAR NUMBER + of is appropriate when referring to A SPECIFIC, KNOWN GROUP.
Correct:
One hundred of the museum's paintings were saved.
The company sold two thousand of its most expensive computers.

SINGULAR NUMBER + of is not appropriate when referring AN ENTIRE CATEGORY.
Incorrect:
One hundred of paintings were saved.
The company sold two thousand of computers.

D: colonies that have several hundred of them
Here, them seems to refer to bumblebees, conveying the following meaning:
several hundred of bumblebees.
Since SINGULAR NUMBER + of cannot serve to refer an entire category, eliminate D.

To refer to an entire category, we can use PLURAL NUMBER + of.
Correct:
HUNDREDS of paintings were saved.
The company sold THOUSANDS of computers.
MILLIONS of bumblebees live in colonies.