Why did king laius send his servant to leave his new born son in the wilderness to die?

Oedipus was the son. Having been childless for some time, Laius consulted the Oracle of Apollo at Delphi. The Oracle prophesied that any son born to Laius would kill him. In an attempt to prevent this prophecy's fulfillment, Laius had his ankles pierced and tethered together so that he could not crawl; Jocasta (his queen) then gave the boy to a servant to abandon on the nearby mountain.

In short, King Laius of Thebes wished to thwart a prophecy, so he sent a servant to leave Oedipus to die in the wilderness. However, the shepherd took pity on the baby and passed him to another shepherd who gave Oedipus to another King.

i would pick a. i think this is more of a personal question though.

it was surely an odd creature that one made up by reading the historians first and the poets afterwards a worm winged like an eagle; the spirit of life and elegance and charm,   in a kitchen chopping up suet. but these creatures, monst'r however entertaining to the imagination, hast no existence in fact. what one might doth to bringeth h'r to life wast to bethink poetically and prosaically at one and the same moment,   thus keeping in toucheth with fact—that the lady is mrs martin, ag'd thirty-six, did dress in blue, wearing a black coxcomb and brown shoeth; but not losing sight of fiction eith'r—that the lady is a vessel in which all s'rts of spirits and f'rces art coursing and flashing p'rpetually. the moment, howev'r, yond one tries this method with the elizabethan mistress, one brancheth of illumination fails; one is did hold up by the scarcity of facts.   one knoweth nothing detailed, nothing p'rfectly true and substantial about h'r.   hist'ry scarcely mentions h'r.   and i did turn to professeth'r trevelyan again to seeth what hist'ry meanteth to that gent.   i hath found by looking at his chapt'r headings yond t meanteth.