What is the quantum of evidence required in labor cases? (2012 BAR)

a. The degree of proof which produces the conclusion that the employee is guilty of the offense charged in an unprejudiced mind;
b. Such amount of relevant evidence which a reasonable mind might accept as adequate to justify a conclusion;
c. That degree of proof which is greater in weight than the opposing party's evidence;
d. Such evidence which must be highly and substantially more probable to be true than not which convinces the trier of facts of its factuality.