Select the most appropriate word to fill in the blank.

She is highly skilled _____ dealing with difficult customers.

at

The most appropriate word to fill in the blank is:

☀ at

The sentence would read: "She is highly skilled at dealing with difficult customers."

Explanation: "Skilled at" is the correct phrase to indicate proficiency or expertise in a particular area. The other options don't fit the context:

• Of: This doesn't fit the context of indicating skill in dealing with difficult customers.

• Into: This preposition doesn't fit the context of indicating skill in dealing with difficult customers.

• On: This preposition doesn't fit the context of indicating skill in dealing with difficult customers.