The first word, "better" describes the morning, which is a comparative form of good. The second word "easier" describes the day, which means less difficult to do or less demanding. So the option "better, easier" is the appropriate word that completes the sentence.

The comparative form of an adjective is used to compare two things, people, or situations. In this sentence, the morning is being compared to a state where breakfast is not taken and the day is being compared to a day where breakfast was not taken. The sentence implies that taking the time to eat a good breakfast makes the morning better (in comparison to not taking breakfast) and the day easier (in comparison to not taking breakfast). It’s also to indicate that there is a difference between the two states and the word "better" and "easier" are used to express that difference. The morning is better and the day is easier due to taking the time to eat a good breakfast.