answer and explain the ff:

1.A contract of sale was entered into by and between A and B purporting to be a sale of a 12-hectare lot for P300,000 in 1970. A died in 1975, and the heirs of A discovered the sale in 1995. They filed an action for nullification of the deed of sale contending that their father never received the amount of P300,000. B filed an answer contending that the action has already prescribed, the same having been filed after ten years. Is the defense proper? Why?

2.A bought from B a building together with the land upon which it is built. One of the conditions is that upon the payment of 1/2 of its value, B would assign his rights over the leases to which B did not comply. A demanded the refund of his money, and since B refused, he filed a suit for collection of sum of money. B filed a motion to dismiss on the ground that the contract is unenforceable since it is only an oral one. Is the contention of B correct? Explain.

3. Dore and Mifa entered into a contract whereby Mifa's services were engaged for the purpose of constructing a building on the lot belonging to Dore. Sola, a friend of Mifa, went to see Dore and told him that Mifa is well-known for her failure to finish her contracts within the period agreed upon, prompting Dore to cancel her contract with Mifa and awarded the same to Sola. Can Sola be held liable for damages? Explain.