Confuse with example of call/put option in real life

Dear Tutor,

When revising this paper, I am wondering with 1 example in real life and don’t know whether it is the call or put option.

Initial offer: Company X has an agreement with Government to build 2,500 miles of highway across the country during 5 years.
Revised offer: Company X offers to build 1,500 miles of highway in urban area at first, and have the option to build remaining 1,000 miles of highway in the next 4 years.

My question here is that option to build remaining 1,000 miles of highway is call or put option, and why?

My initial view is that build the highway, company X will receive money -> it is option to sell something because when completing the highway, company X will receive money. So it is the put option.

However, on the other hand, I am wondering whether “underlying asset” is the “right to build the highway”, and company X has to pay money to buy this right. In this assumption, it is the call option.

Because not being sure with both ways of thinking, I do not know what is right and what is wrong, so please help me clarify.