B. A possessive noun should have its instead of it's (which is a contraction for it is). Β
For A. Β Diana is a singular noun and the apostrophe should come after the r instead of after the s.
For C. The duck would've dunked ITS instead of IT'S beak since it is possessive.
For D. Β You do not need to put an apostrophe since theirs is already a possessive noun.