Sentence Correction

Since dolphins have large tongues and do not have large teeth, food must be broken down in another way before reaching the stomach, and for this reason, dolphins have long throats in which the plants they swallow are used to grind their food.

A) before reaching the stomach, and for this reason dolphins have long throats in which the plants they swallow are used to grind their food.

B) before it reaches the stomach, and for this reason, dolphins have long throats in which the plants they have swallowed is used to grind their food.

C) before it reaches the stomach, and for this reason, dolphins have long throats in which the plants they swallow are used to grind their food.

D) before reaching the stomach, and for this reason, dolphins have long throats in which the plants they have swallowed is used to grind their food.

E) before it reaches the stomach, and for this reason, dolphins have long throats in which the plants they have swallowed are used to grind their food.

Why OA is E? Shouldn't it be [spoiler]C because simple present is used for explaining the general concepts? [/spoiler]

Source: 2minuteGMAT daily questions

I have another doubt, in all the options

is 'their' not ambiguous, since both dolphins and plants are in the same sentence.

manu.pant wrote:I have another doubt, in all the options

is 'their' not ambiguous, since both dolphins and plants are in the same sentence.

I agree that the use of their is ambiguous but since none of the options is resolving the ambiguity we'll have to go with the choice which resolves other errors present in the original sentence.

i feel what rjain84 has said is very right :simple tense is used for explaining general facts such as sun rises in the east . But in this case we need "have swallowed" instead "swallow" because we need to show the sequencing of the events :swallowing has happened before grinding of food .hence E

we use simple present tense for general facts but the act of grinding happened after swallowing. so the use of Have swallowed is right.
The next is about "their" the sentence is "dolphins have long throats in which the plants they have swallowed are used to grind their food" this is the complete sentence with subject dolphins and "their" is refering to dolphins.

Tommy Wallach wrote:Hey Guys,

Sorry, but the GMAT wouldn't do this. There isn't enough of a difference between C and E. There's no need to set up tense order here, because the two things actually happen simultaneously (plants and food are eaten, and the plants grind up the food). I don't see a strong enough case for E over C to make this realistic.

Could you make the case that the present perfect makes a bit more sense? Sure. But enough to build a split/question around? I don't think so...

-t

Thanks..yet again, Tommy!