Correct Answer: Unreflective

Solution : The second option is correct.

Pensive suggests a state of deep contemplation, or reflection.

Unreflective indicates a lack of contemplation or thoughtfulness. It is used for people who don't engage in deep reflection of their thoughts, making it the appropriate antonym for pensive .

The meanings of the other options are as follows:

• Frivolous is used for activities or objects that are not considered important or serious.
• Hollow means having empty space inside.
• Goofy means silly.