D. meeting one particular dog
A gerund phrase begins with a -ing word and then includes any modifiers and objects, so A, B and C are not the correct answers.
If you asked your friend to hand you a book and he handed you a pencil instead, it is phonology as a language system that is most likely broken down. Phonology deals with systems of sounds which includes phonetics in a specific language.
The answer would be the first choice.
