If the period of a wave decreases, its frequency must

Increase

Explanation:

The time period depicts the amount of time taken for completing one cycle of vibration. While frequency is the measurement of a number of cycles in a unit time.  

Therefore, both the period of wave and frequency are inversely proportional to each other. The higher will be the time period, the lower will be the frequency and vice versa.  

The answer is B. This is stipulated in the theory of abiogenesis. The atmosphere in early earth was composed of compounds such as methane, hydrogen sulfide, and ammonia. This reducing environment was right for the formation of biomolecules . This early life is similar to that found in hydrothermal vents deep in the oceans, today.