Which of the following sentences correctly uses verb tense and mood?

The sentence "They have decided to join us" correctly uses verb tense and mood. In this case, the present perfect tense "have decided" indicates an action that was completed at an indefinite time in the past but is relevant to the present situation. The inclusion of "to join us" further clarifies the intention of their decision, highlighting both the completion of the decision-making process and its ongoing implications.

The other sentences have grammatical errors. The first sentence incorrectly mixes the present tense "goes" with the adverb "yesterday," which refers to the past. The second sentence uses "will went," which is a combination of future and past tenses that does not work together. Finally, the last sentence uses "seen," which is the past participle form instead of the simple past "saw." Thus, the correct choice stands out due to its proper construction and clear communication of tense and mood.