TRAP: This is an easy question, but take note: if your strengths do not match the key points of the job description, you will not be considered a strong candidate.
TRICK: Highlight your strengths that most match the job description's key points. If you're applying for a digital marketing position, then say that your strength is digital marketing. If you are applying for a graphic designer position, highlight your Design skills. Match yourself to the company's needs.
Mention the rest of your strengths as well. The more you market yourself, the more you will be in demand. Talk about your strong communication skills such as social skills or teamwork—these are some of the most desirable skills.