Does higher [OH] not entail higher pH? A student has equal volumes of $\pu{1.0 mol dm-3}$ sodium hydroxide and ammonia solutions. Which statement about the solutions is correct?
A. Sodium hydroxide has a lower electrical conductivity than ammonia.
B. Sodium hydroxide has a higher hydrogen ion concentration than ammonia.
C. Sodium hydroxide has a higher pH than ammonia.
D. Sodium hydroxide has a higher hydroxide ion concentration than ammonia.

The answer is C, and I understand why. What I do not understand is why D isn't correct also? Could someone clarify this for me?
See this website. Essentially it's a misprint in the IB Chem testbank.

https://www.thinkib.net/chemistry/blog/8944/multiple-choice-answers

There's a correct rewording for D that makes C the only correct answer, according to the link I just posted.