Renting -Under option

I have made an offer to rent an apartment.

It was accepted.

I received a draft lease.

I may not be able to take the apartment due to a need for a bigger place.

I have not signed a lease

Can I look elsewhere or am I tied to the apartment?
If you signed the under option agreement Normally you can refused but you have to check conditions in the offer agreement. But if you did not sign any documents then i think you can just let them know that you are no longer interested. Before refusing please review what you have agreed.
I afraid not an easy answer.
Thank you.
Thanks again,

Just to check:

The only paper work I signed was the document the agent told me was my offer. My name address, rent offer, salary etc, possible move in date?

The agent said the owner needed this and would then decide to accept the offer or not.

I hadn't heard about an 'offer agreement'. I don't think that was it?
Read 'option agreement'  above