On February 1st, Zak offers to paint Mo's house for $5,000. Zak tells Mo that he has until February 10th to accept the offer. (1)

Mo responds to Zak's offer on February 5th stating he would like Zak to paint his house but proposes 4,000 instead. (2)

Zak responds that is too low and offers $4500 and that Mo should let him know if that is ok by February 10th. (3)

On February 11th Mo accepts the proposal of $4500. (4)

Zak refuses to paint Mo's house, and Mo sues stating Zak and Mo have a contract.

1. What is the nature of line (1)?
2. What is the nature of line (2)?
3. What is the nature of line (3)?
4. What is the nature of line (4)?
5. Do Zak and Mo have a contract? Why or Why not?

Explain.