Sentence Correction

I'm just a beginner on GMAT thus I'm reading my very first book- The Princeton Review "Manual for GMAT". Inside the book there are example questions with no answer/explanation.
I need expert's help to identify the answer to these questions and somehow explaining why it's so.

So here we go:

1. The Department of Education has concluded that if children learn to read and did math from an early age, they will require less remedial work in later school years.

A did math from an early age, they will require less remedial work in later school years
B did math from an early age, they require in later school years less remedial work
C do math from an early age, they require less remedial work in later school years
D do math from an early age, they will be required in later school years to do less remedial work
E did math from an early age, less remedial work will be required in later school years

I think the answer here is C. But not sure about the second part (will/present simple) of the sentence.

2. Although Smith once championed the charity, he changed his mind after a journalist linked its origin to a corrupt individual.

A once championed the charity
B had once championed the charity
C has once championed the charity
D was a champion of the charity once
E championed the charity at one time

Again my guess here is 'A', but 'D' sounds more right.

Any help from experts will be appreciated! Thank you in advance!

It'd be great if anyone who knows how to answer to reply since i'm stuck on these questions...

bek_gmat wrote:I'm just a beginner on GMAT thus I'm reading my very first book- The Princeton Review "Manual for GMAT". Inside the book there are example questions with no answer/explanation.
I need expert's help to identify the answer to these questions and somehow explaining why it's so.

So here we go:

1. The Department of Education has concluded that if children learn to read and did math from an early age, they will require less remedial work in later school years.

A did math from an early age, they will require less remedial work in later school years
B did math from an early age, they require in later school years less remedial work
C do math from an early age, they require less remedial work in later school years
D do math from an early age, they will be required in later school years to do less remedial work
E did math from an early age, less remedial work will be required in later school years

I think the answer here is C. But not sure about the second part (will/present simple) of the sentence.

2. Although Smith once championed the charity, he changed his mind after a journalist linked its origin to a corrupt individual.

A once championed the charity
B had once championed the charity
C has once championed the charity
D was a champion of the charity once
E championed the charity at one time

Again my guess here is 'A', but 'D' sounds more right.

Any help from experts will be appreciated! Thank you in advance!

For first question C is wright because of the simple tense they require as it keeps both the initial and latter part of the sentence parallel

For second question I would go with B because one action is followed by a later action therefore, past perfect tense should be followed by simple past tense