When the choice is between an infinitive and a gerund, the following rule is recommended by experts:

"On the GMAT, if you have to choose between an "ing" verb and the infinitive AFTER another verb, always choose the infinitive. When the verb does not follow another verb, the participle ("ing" form) is usually correct."

Bearing this in mind, I was solving this particular SC question -

Dirt roads may evoke the bucolic simplicity of another century, but financially strained townships point out that dirt roads cost twice as much as maintaining paved roads.

(A) dirt roads cost twice as much as maintaining paved roads
(B) dirt roads cost twice as much to maintain as paved roads do
(C) maintaining dirt roads costs twice as much as paved roads do
(D) maintaining dirt roads costs twice as much as it does for paved roads
(E) to maintain dirt roads costs twice as much as for paved roads

Now, normally I would have chosen B straight off because it sounds good and the grammar is correct...the only thing that struck me was "to maintain". So I applied the rule and chose D. The only possible flaw in this option was the pronoun "it", otherwise the sentence looked OK to me. So blinded by the rule I chose it over B and to my surprise got it wrong.

I would be glad if the experts could shed some more light on this rule, did I not apply it correctly or are there some exceptions to this rule? Any pointers are welcome.....

Thanks

Cheers
Sid