Which sentence uses the word them as an indirect object?

a.the students are at the launch site with them.
b. leo sent them a postcard from nasa.
c.space exploration is a fascinating subject to them.
d.the tour guide took them around nasa.

I am pretty sure that the sentence which uses the word ''them'' as an indirect object is the last one : d.The tour guide took them around NASA.  As you know,  direct object stands near the verb in order to point on the thing that being acted upon. Here is two main points : took-V, them-indirect object, as a recipient of the direct one.

Do hope you will find it useful.

Writing a Critique:

describe: give the reader a sense of the writer's overall purpose and intent.

analyze: examine how the structure and language of the text convey its meaning.

interpret: state the significance or importance of each part of the text.

assess: make a judgment of the work's worth or value.

Explanation: