I wonder what's the difference between the synonymous words:
For instance, I wonder if any of these three choices "doesn't" work in my scenario (to me they all work without any considerable change in meaning):
After lots of efforts he couldn't achieve that position in their company. He studied for its enterance exam for more than 3 months. Though he passed the test, but unfortunately he was rejected in the interview. Perhaps, he lacked the .................. practical skills for the job.
a. needed (to me it sounds casual and normal)
b. required (it sounds like a formal word to me)
c. requisite (more formal than "required")