Compound of Phrasal and Prepositional Verb

[spoon]

Hello,

You may see this collocations like 'look up to' or 'put up with'.

I'm now studyint syntax, there are some questions about 'the strings of words above'.

(a) He looks up to Mary.

after applied Movement rule,

(b) Who does he look up to?

(c) To who does he look up?

(d) Up to who does he look?


I think (b) and (c) are grammatical, but (d) is not.

Am I right?

Thanks in advance.
Spoon

[Tdol]

c/d- should be 'whom' for me, though both are very ugly.

[spoon]

c/d- should be 'whom' for me, though both are very ugly.

Then, being replaced who with 'whom', are they acceptible or grammatical?

[DavyBCN]

Then, being replaced who with 'whom', are they acceptible or grammatical?

as tdol said, using whom c and d would be grammatically correct - but they are so unnatural.