Directions: Fill in the blanks with the suitable option.

An increase in population, without an increase in economic level, _______ result in a lower standard of living.

The subject 'increase' is singular, so it needs the singular verb form 'tends to' followed by the base form 'result'. 'Tending to' would make the sentence fragment, 'will tend' changes the meaning to certainty, and 'tends' alone would require the base form 'to result' immediately after. The correct phrase is 'tends to result in'.