Final answer:
The most dangerous time for high tides at the seashore is midnight at a new moon due to the occurrence of spring tides when the Earth, Moon, and Sun are aligned. correct option is A.
Step-by-step explanation:
The most dangerous time at the seashore due to very high tides is a) Midnight at new moon. This is because the highest tides, known as spring tides, occur when the Earth, the Moon, and the Sun are aligned. During a new moon, this alignment results in the combined gravitational pull of the Moon and the Sun on the Earth's oceans, leading to higher than normal tides. Alternatively, the smallest tides, called neap tides, happen when the Sun lies at 90° to the Earth-Moon alignment, such as during the first and third quarters of the Moon's phase.