Dear Poorvasha,

I'm happy to respond.

It's true that the "in that" structure is very sophisticated and formal, but all the language on the GMAT SC is sophisticated and formal, so this structure usually fits on the GMAT SC.

In this sentence, either "because" or "in that" would be correct. The problem in (A) is that the noun-modifying phrase that follows the underlined section is awkward--this phrase is meant to modify "tissue," not "tooth and bone," which it touches. The question of the phrase's target noun is ambiguous and muddy in (A), whereas (E) concisely cleans up this ambiguity.

Does all this make sense?
Mike
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My POE:
A) Was stuck between A and E and eliminated A because it sounds like "not normally found" is modifying BONE, but should be modifying tissues
B) LIKE is wrong, TISSUES are not LIKE TOOTH AND BONE
C) Same as B
D) COMPOSITION is being modified, but it should actually be tissues
E) CORRECT

Teratomas are unusual forms of cancer because they are composed of tissues such as tooth and bone not normally found in the organ in which the tumor appears.

A is incorrect because the logical meaning is that the cancer is composed of tooth and bone not normally found in... which indicates that the cancer could typically be composed of tooth and bone, but not the type of tooth and bone found in the Teratomas.

If we had commas -...., such as tooth and bone,.... then this would be a perfect sentence.

The Teratomas are unusual because their composition is composed of tissues not normally found in x.

Had to read extremely carefully to get this illogical change.

B and C are out because of the use of Like here. We use for example/ such as to give examples.
There are more illogical meaning issues with B
(B) because they are composed of tissues like tooth and bone that are
(C) because they are composed of tissues, like tooth and bone, tissues

D is illogical - its not the composition itself that isn't found in the cancer location it's what the composition is made up of - the types of tissues
(D) in that their composition, tissues such as tooth and bone, is

(E) in that they are composed of tissues such as tooth and bone, tissues

E is structured as <independent clause> + [,] + <noun modifier>
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