A. disciplined
B. naive
C. strict
D. loose
tactful : having or showing skill and sensitivity in dealing with others or with difficult issues.
disciplined : showing a controlled form of behaviour or way of working.
naive : showing a lack of experience, wisdom, or judgement.
strict : demanding that rules concerning behaviour are obeyed and observed.
loose : not firmly or tightly fixed in place; detached or able to be detached.
Antonym of tactful is naive