The correct answer is (2) Inhibiting differentiation of stem cells.

Option-wise explanation

(1) Stimulating growth of cell – Partly true but not the key use here

LIF is a pleiotropic cytokine that can support survival or proliferation of some hematopoietic and other cell types, but its hallmark use in standard animal cell culture protocols is not simply “growth stimulation”.​
The exam focuses on its classic role in embryonic stem (ES) cell culture, where growth is coupled with maintenance of the undifferentiated state.

(2) Inhibiting differentiation of stem cells – Correct

In mouse embryonic stem cell cultures, LIF is routinely added to the medium to prevent spontaneous differentiation and maintain pluripotency.​
LIF activates JAK/STAT3 and other pathways, promoting self‑renewal so that ES cells remain undifferentiated as long as LIF is present. Removing LIF pushes ES cells toward differentiation.​

(3) Inducing morphogenesis – Incorrect in this context

Although LIF has roles in development and implantation in vivo, in standard in vitro animal cell culture it is not used as a morphogen to drive organized morphogenesis.
Instead, it is used to block differentiation, particularly in ES and some neural stem cell systems.​

(4) Arrest cells at mitosis – Incorrect

LIF does not function as a mitotic inhibitor like nocodazole or colchicine.
Its primary documented action in ES cell culture is to support self‑renewal and inhibit differentiation, not to arrest the cell cycle at mitosis.​

Therefore, among the given choices, the specific and best‑known use of leukemia inhibitory factor in animal cell culture is (2) inhibiting differentiation of stem cells.