When faced with obstacles, a person's level of persistence determines how hard he or she will keep trying to perform a chosen behavior successfully

A buyer and a seller enter into a purchase and sale agreement. The agreement provides that closing must take place by September 30. A clause states that a party's failure to be ready by a date specified in the contract will constitute a breach of the contract. What is the name of this clause?

A. A habendum clause B. A contingency clause C. A time of the essence clause D. A closing clause

Which of the following is NOT one of the most widely used platforms to transmit social messages?

A) intranet wikis B) branded blogs and micro-blogs C) social networks D) widgets, games and apps E) mobile phones