Select the most appropriate option to substitute the underlined segment in the given sentence. If there is no need to substitute it, select No substitution required.A study has uncovered a previously overlooked law of natural selection based on "survival of the slacker". that is, spend all day lazing about could be good for human evolution.

• A. No substitution required
• B. spending all day lazing about must be good for human evolution
• C. spend all day lazing about will be good for human evolution
• D. spending all day lazing about could be good for human evolution