Final answer:
Chocolate-chip ice cream is a heterogeneous mixture, while green ink, cake batter, and cooking oil are homogeneous mixtures.
Step-by-step explanation:
a) Chocolate-chip ice cream is a heterogeneous mixture. It can be easily identified as a mixture because it contains visible different components like chocolate chips and ice cream.
b) Green ink is a homogeneous mixture. It appears to be the same throughout and does not separate into different components.
c) Cake batter is a heterogeneous mixture. It contains various ingredients like flour, sugar, eggs, and milk, which can be visually distinguished.
d) Cooking oil is a homogeneous mixture. It appears as a single phase and does not show visible separation of components.