Auxin and making more cytoplasm
 

I am teaching the botany part of second semester biology at the college
level and have come across something that may contradict what I've been
teaching. In the 8th edition of the Campbell, Reese, etc. of Biology, on
page 828, the last paragraph, under the heading of "The role of auxin in
cell elongation"reads:

Auxin also rapidly alters gene expression, causing cells in the
region of elongation to produce new proteins within minutes. Some of
these proteins are short-lived transcription factors that repress or
activate the expression of other genes. For sustained growth after this
initial spurt, cells must make more cytoplasm and wall material. Auxin
also stimulates this sustained growth response.

Does the last sentence mean that auxin stimulates the cell to make more
cytoplasm and wall material OR does it simply mean that it stimulates the
sustain growth response, but does not stimulate the cell to make more
cytoplasm and cell wall material. I have always taught that auxin
increases cell growth, but does not stimulate the cell to make more
cytoplasm nor does it have anything to do with making more cell wall
material.

Furthermore, When I go to the Mastering Biology web page that is set up
to be used for this text, there is a question that reads:

Which of the following has not been established as an aspect of auxin's
role in cell elongation?... The answer choices we

Auxin increases the quantity of cytoplasm in the cell.
Auxin activity permits an increase in turgor pressure.
Auxin stimulates proton pumps.
Auxin instigates a loosening of cell wall fibers.
Through auxin activity, vacuoles increase in size

The answer Mastering Biology gives is the first choice, "auxin increases
the quantity of cytoplasm in the cell". So am I correct in saying that
perhaps the wording in the last paragraph, in the text, is ambiguous and
that auxin has nothing to do with increasing the quantity of cytoplasm in
the cell? Thanks for any comments on this question.