Find the Synonym: 'Demanding and Challenging' Vocabulary Quiz

algorithm, arduous, ascetic, austerity, benchmark, challenging, climb, complex, complicated, compulsory, crucible, degrade, demanding, dissertation, drudgery, evade, evasive, excruciating, exigent, finicky, formidable, grueling, implacable, insist, insistence, insistent, insolvent, insuperable, insurmountable, intransigent, laborious, mandatory, meteorology, obdurate, obligatory, onerous, premature, protester, Pyrrhic, rapacity, rapid, rebel, rebellious, recalcitrant, requisition, stringent, stubborn, summit, surpass, taxing, toil, travail, unapproachable, undeterred, unfathomable, unrelenting