Select the most appropriate option to fill in the blank.

Today’s graduates should ______ their skills constantly to be able to excel in their career and life.

upgrade

The correct option to fill in the blank is upgrade.

The sentence is about the importance of upgrading skills for today's graduates to excel in their career and life. The word "upgrade" means to improve or make something better. It is the most appropriate word to use in this context, as it conveys the meaning of the graduates constantly improving their skills to stay ahead of the curve.

The other options are not as appropriate.

• Dilute means to make something less concentrated or pure. This is not the right word to use, as it does not make sense to say that graduates should dilute their skills.
• Active means engaged in activity or effort. This is not the right word to use, as it does not convey the same meaning as "upgrade."
• Encourage means to give someone support or confidence to do something. This is not the right word to use, as it does not make sense to say that graduates should encourage their skills.