Tom’s willingness to work impressed his employer.

identify the words in bold.
a.

preposition
b.

verb
c.

gerund
d.

infinitive

D:To work is an infinitive

Explanation:

To is  part of the infinitive, it is an infinitive particle. Work is a verb (or bare infinitive, without the infinitive particle. ); the union of to and work  forms the infinitive (to work). In the sentence "She goes to work", to  is a preposition and work is a noun. Working is a gerund. Working hard is one of Tom's many characteristics that impressed his employer.

she is outspoken and direct