Surprisingly, much of the most glaring errors contained in the report

OFFICIAL EXPLANATION




• Split #1: MANY vs. MUCH

Errors are countable.
We use many with countable nouns: Many bodies of water are landlocked.
We use much with uncountable nouns: Much of the water is drinkable.
Options A and B incorrectly use much to describe errors.
ELIMINATE A and B

• Split #2: SUBJECT/VERB agreement

Many is a plural quantifier (also called a "determiner") on the GMAT and in 99 percent of all writing.
Correct: Many . . . errors . . . are
Option E incorrectly states: . . . many . . . errors . . . is

(Many is singular when followed by an indefinite article and a singular noun:
Many a man has been captivated by her smile. → That usage is literary, somewhat archaic, and rare.)

ELIMINATE E

• Split #3: Option C v. D

→ → failure to verify in (D) is better than failure of verifying in (C)

All native speakers should cringe when they read failure of verifying.
The phrase is not idiomatic. In context, the phrase is a stylistic disaster.
The noun is an awkward gerund (verbING), but even the dedicated noun (failure of verification) would not be good.

Failure to X is more active and forceful than failure of Xing.

Usage
To describe something that should have been done but was not, use failure to verb.
→ Her failure to comply with the dress code was predictable.
(Not Her failure of compliance/complying with the dress code...)
→ The elected officials' failure to uphold the Constitution will come back to haunt them politically.
(Not The officials failure of upholding the Constitution...)
→ My failure to read the instructions resulted in a hot mess.
(Not My failure of reading the instructions...)

To describe a missing noun or the lack of a noun, use failure of noun.
→ The delay in vaccine distribution was caused by a failure of leadership.
→ Ridiculous and disproven conspiracy theories display not overactive imagination but rather failure of imagination.

Option D is better than option C.
ELIMINATE C

The best answer is D.

Notes
→ I would not eliminate C because it uses "the more glaring errors," although I would let it "tilt" the balance for me towards D.

When more is used with the and a descriptor, the phrase itself implies two groups (and perhaps two groupings on a spectrum).
→ The more experienced soldiers planned the escape.
(The less experienced soldiers did not plan the escape.)
→ More educated citizens tend to skew polls because they answer such polls frequently [whereas less educated citizens answer polls less frequently].

"The more glaring" implicitly creates two groups of errors: those that are more and less glaring.
The construction is not wrong, but I recall having seen only one or two official questions in which "the more _____" was used this way.

Google these words with the quotation marks and scroll down to the "regular" sections:
"the more experienced" new york times

EDIT: "contained" is a past participle, not a simple past tense verb.
Contained is part of a reduced relative clause, this way: . . . many of the errors [that are/were] contained in the report [can/could] be attributed to a simple failure to verify ...

COMMENTS

AnkitHRD , sudeshpatodiya , and chiragarora001 , welcome to SC Butler.

I'm a little under the weather, so I'll keep this short.

I'm glad to have such a diverse crew. It's always good to see newcomers, occasional visitors, veterans, and stalwarts.

These answers range from very good to excellent. Kudos to all.