In meteorology, a trough refers to an elongated area of relatively low atmospheric pressure, often associated with fronts. Contrastingly, a ridge refers to an elongated area of relatively high atmospheric pressure, typically associated with a high-pressure system. Therefore, option 1 is the correct answer.

Option 2 suggests that both a trough and a ridge are elongated areas of low pressure which is inaccurate because a ridge is an area of high pressure.

Option 3 states that both a trough and a ridge are elongated areas of high pressure. It is false since a trough is a region of low pressure.

Option 4 mentions that a trough and a ridge are elongated areas of high pressure and low pressure respectively. This statement switches the definitions of trough and ridge thus making it incorrect.