Problem with word order

[Jupiter]

Hello teachers,

Please see the following:

The physical phenomenon.................use to obtain water from the soil is osmosis.

1/ plants have roots
2/ plants are rooted
3/ that plant roots
4/ what plant roots
Which one is the correct answer? And why?

Thanks in advance

Jupiter

[Conchita]

Here again, it would be interesting to see what you think first.

Hint: 'plant roots' are a subject.

[Jupiter]

Hi Conchita,

Thanks again :D

3/ that plant roots would be the correct one.

Jupiter