Answer: Option (A) is the correct answer.
Step-by-step explanation:
When a substance is heated then less dense (hotter) material rises and more denser (colder) material sink due to the influence of gravity. As a result, heat transfer form hotter to colder substance and this process is known as convection.
For example, noodles in a hot water. Noddles being more denser (colder) will sink at the bottom and water being less dense will rise.
Thus, we can conclude that out of the given options, noodles rising and falling in a pot of boiling water is best categorized as heat transfer by convection.