question

brainteaser, conundrum, poser, puzzle, quiz, riddle, stickler, stumper, toughie (also toughy)

interrogatory

poll, questionnaire, survey

inquisition, interrogating, interrogation, questioning

examination, exploration, inquest, investigation, probe, probing, research, study

compunction, doubt, misgiving, qualm, scruple

misunderstanding

cavil, niggle [chiefly British], quibble

argument, conflict, debate, dispute, dissent, hassle, quarrel, squabble, static

censure, criticism

defiance, disobedience, rebellion

distrust, distrustfulness, dubiety, dubitation [archaic], incertitude, indetermination, misdoubt, mistrust, mistrustfulness, reservation, skepticism, suspicion, uncertainty

qualmishness, unease, uneasiness

reluctance, unwillingness

subject matter

talking point

count, idea, point, purpose

consideration, issue, problem

body, bulk, burden, centerpiece, core, crux, essence, fundamental, generality, gist, grist, heart, kernel, keynote, main, marrow, mass, net, nub, nubbin, nucleus, pith, pivot, purport, quick, staple, substance, sum

basis

bottom, essential, essentiality

affair, argument, debate

doubt, mistrust

kick (about), object (to), protest

combat, fight, oppose, resist

muse (upon), reflect (on or upon), reminisce

analyze, explore, review

conclude, reason

second-guess, speculate (about)

brood (about or over), dwell (on or upon), fixate (on or upon), fret (about or over), obsess (about or over)

believe, conceive, opine

absorb, assimilate, digest, drink (in)

disbelieve, discount, discredit, negate

besiege, bombard, cross-examine, cross-question, examine, pump

poll, survey

debrief

cross-examine, cross-question

annoy, harass, hound, pester

canvass (also canvas), poll