Please explain why E is right ?

[pankajjindal]

A group of students in an Indian village has been selected for testing a new low-cost electronic notepad being built around a new class of green, power-stingy microchips that use a fraction of the electricity of current computer chips
A. has been selected for testing a new low-cost electronic notepad being built around a new class of green, power-stingy microchips that use a fraction of the electricity of current computer chips
B. have been selected to test a new low-cost electronic notepad being built around a new class of green, power-stingy microchips that use a fraction of the electricity used by current computer chips
C. has been selected to test a new low-cost electronic notepad to be built on a new class of green microchips, which are also power-stingy and which use a fraction of the electricity used by current computer chips
D. have been selected for testing a new low-cost electronic notepad being built around a new class of green, power-stingy microchips that use a fraction of the electricity of current computer chips
E. has been selected to test a new low-cost electronic notepad being built around a new class of green, power-stingy microchips that use a fraction of the electricity used by current computer chips

[Jim@StratusPrep]

For proper Subject-Verb agreement the sentence must read "A group ... has been ..." leaving A, C and E.

A should be eliminated because 'for testing' does not show intent the same way the infinitive form of to test does.

C should be eliminated because the infinitive form of to be is incorrect - you are not showing intent.

[Lifetron]

A group of students in an Indian village has been selected for testing a new low-cost electronic notepad being built around a new class of green, power-stingy microchips that use a fraction of the electricity of current computer chips
A. has been selected for testing a new low-cost electronic notepad being built around a new class of green, power-stingy microchips that use a fraction of the electricity of current computer chips
B. have been selected to test a new low-cost electronic notepad being built around a new class of green, power-stingy microchips that use a fraction of the electricity used by current computer chips
C. has been selected to test a new low-cost electronic notepad to be built on a new class of green microchips, which are also power-stingy and which use a fraction of the electricity used by current computer chips
D. have been selected for testing a new low-cost electronic notepad being built around a new class of green, power-stingy microchips that use a fraction of the electricity of current computer chips
E. has been selected to test a new low-cost electronic notepad being built around a new class of green, power-stingy microchips that use a fraction of the electricity used by current computer chips

Group is singular - Eliminate B and D
C - "notepad to be built" -> You can't test a notebook that's not yet built !
A - "to test" is preferred on GMAT to "for testing". "electricity of current computer chips" sounds like Chips have some electricity !

Hence E !

Please use spoilers for answers, so that others can actually try the questions.