Spontaneous mouse tumor models can be created by:
a. transgenic mice technology
b. knocking out tumour suppressor genes
c. UV radiation
d. Feeding mice carcinogens

Can be more than one correct answer

All four approaches could lead to tumors. However, I would not call
the induction of tumors with carcinogens or with UV a "spontaneous"
tumor model, because it is deliberate induction with a known
tumorigenic agent. I'm loath to put this in as an answer, because it
really depends on the view taken by your lecturer as what is meant by
"spontaneous".

agree with tehuti that u probably need to check with your lecturer
what he/she means by spontaneous.

but obviously a and b is out, becos they specifically create cancer
(i.e. not spontaneous at all)

for uv and carcinogens, it depends on the dosage, it is
pseudo-spontaneous, if you expose the poor mouse to continual
tumorigenic agents sooner or later they would develop tumors, i guess
you can call them spontaneous in the sense that you sometimes cannot
determine what type of tumors would occur..although by and large uv
agents usually trigger some type of skin cancer tumors and the
chemicals are more likely to trigger the liver cancer type tumors.

Actually, I meant it the other way round. Mouse b would have missing
some of the normal control mechanisms which prevent the occurrence of
tumours, and mouse a could be engineered to have a fault in others. 
Therefore, these mice would develop tumours spontaneously without any
specific treatment on the part of the experimenter. By asking what is
meant by spontaneous, I was thinking along the lines that, for
example, inducing tumours with UV light mimics a process that one
might or might not call spontaneous when it happens in real life.