Gina doesn't make enough money at her current job, therefore, she is searching for a higher paying one

Examples of unenforceable oral contracts are:

a. an oral promise to guarantee the additional duties of another. b. an oral agreement to substitute different land for that described in the original contract. c. an oral agreement to extend an employee's contract for six months to a total of two years. d. All of the above.

Evidence of concomitant variation, time order of occurrence of variables, and elimination of other possible causal factors, when combined, demonstrate conclusively that a causal relationship exists

Indicate whether the statement is true or false