Answer: The correct words that complete the sentence are "is" and "its": The colony of ants <u>is</u> making<u> its</u> way up and over the grassy mound.
Explanation: In the sentence provided,<u> "colony", which is a singular noun, is the head of the subject</u>. Moreover,<u> the noun "colony" indicates that a group (of ants, in this case) is working together as a unit.</u> Taking this into consideration, a singular verb has to be used in order to make the subject and the verb agree in number. In that way,<u> "is" is the word that completes the sentence.</u> Furthermore, as "colony" is a singular noun,<u> a singular pronoun needs to be used</u>; therefore,<u> the pronoun </u>that completes the sentence and comes before "way"<u> is "its". </u>