In the context of water bodies, Neap Tides occur:

Correct - A. A neap tide occurs at quadrature - the Sun and Moon at right angles as seen from the Earth, which happens at the Moon's first quarter and last quarter.

Their tide-raising pulls then act across each other instead of together, and the solar bulge partly cancels the lunar one.

The result is the month's smallest tidal range: a lower high tide and a higher low tide. That right-angle geometry is option (a).

Why the others are wrong

• (b)
  when the sun and moon are on the opposite sides — Sun and Moon on opposite sides of the Earth is the full-moon alignment. That is still a straight line, so it produces a spring tide - the largest range, not the smallest.
• (c)
  when there is so much interference by continents — Continents do reshape tides locally, in gulfs, estuaries and funnels like the Bay of Fundy, but the spring-neap cycle is defined by Sun-Moon geometry alone. Landmasses are not what makes a tide neap.
• (d)
  when the earth, moon and sun line up in a straight line — Earth, Moon and Sun in a straight line is syzygy - new moon or full moon - and gives spring tides. This is the exact opposite of the neap condition, which is why it is the most common wrong pick.

Tides are raised by the Moon's gravitational pull and, to a smaller degree, the Sun's - the Sun's tide-raising force is a little under half the Moon's.

When the two act along one line, at new and full moon, the bulges add: spring tides, twice a month, largest range.

When they act at right angles, at the quarters, the bulges work against each other: neap tides, also twice a month, smallest range. Most coasts see two high and two low tides a day, each cycle running about 12 hours 25 minutes.

Key facts

• Neap tides occur twice a month, at the Moon's first quarter and last quarter.
• Spring tides occur at new moon and full moon, when Sun, Earth and Moon are aligned.
• The name spring tide has nothing to do with the season - it refers to the water springing up.
• The Sun's tide-raising force is a little under half the Moon's, so lunar geometry governs the cycle.

Common traps

• Reading spring tide as a seasonal tide of the spring months.
• Choosing the straight-line option because alignment sounds like the special case, when alignment gives spring tides.

No directly related past PYQ was found.