Step 1: Eliminate the mismatches:
'Shameless', 'foolish', and 'wide spoken' do not carry the sense of honesty or openness that 'frank' has.
Step 2: Confirm the match:
'Candid' is the standard synonym for 'frank', both meaning truthful and direct.
Step 3: Final Answer:
Option (iv) 'candid' is correct.