Final answer:
Option C (NH₄CH₃CH₂COOD) and option D (NH2CH2CH₃) are bases.
Step-by-step explanation:
In this question, we need to identify which of the given compounds is a base. A base is a substance that can accept a proton (H+) from an acid to form water. Looking at the options, we can see that option C. NH₄CH₃CH₂COOD and option D. NH2CH2CH₃ both contain the nitrogen-hydrogen (N-H) bond, which can accept a proton. Therefore, option C and option D are bases.