Step 1: Understanding the word "juxtapose."
"Juxtapose" means to place things side by side, usually for comparison or contrast. The synonym should suggest something being next to or placed together.
Step 2: Analyzing the options.
- Collective refers to a group of things, but it doesn’t imply placement side by side.
- Adjacent means next to or adjoining something else, which is the closest in meaning to juxtapose.
- Aligned means arranged in a straight line, but it is not the same as juxtaposing items side by side.
- Distant refers to things that are far apart, which is the opposite of juxtaposing.
Step 3: Conclusion.
"Adjacent" is the most similar in meaning to "juxtapose" because both involve things being placed next to each other.
Thus, the correct answer is 2. Adjacent.
Final Answer:
\[
\boxed{\text{The correct answer is 2. Adjacent.}}
\]