1. compression a space in which particles have been spread apart 2. periodic energy an oscillating source of energy that repeats itself in a regular way 3. pulse a non-recurrent wave 4. rarefaction a space in which particles have been pushed together

Leo is a recruitment executive for a large company. he has identified new labor resource requirements in both the marketing and production departments. what should be his first step in recruiting candidates for the positions? a. conduct background checks of candidates b. make job offers c. arrange interviews d. conduct reference checks e. place job ads on job sites