Which type of trees normally shed all their leaves once every year during a particular season?

Introduction / Context:
Trees and forests are classified in many ways, including whether they keep their leaves throughout the year or shed them seasonally. This classification affects how forests look in different seasons and how they are described in geography and ecology. This question asks you to identify the term for trees that lose their leaves once a year during a particular season, such as in autumn or dry periods.

Given Data / Assumptions:

• The options are deciduous trees, coniferous trees, evergreen trees, and both deciduous and coniferous trees.
• The question refers to trees that shed their leaves once each year in a regular pattern.
• We assume standard definitions from botany and geography.

Concept / Approach:
Deciduous trees are those that lose all or most of their leaves during a particular season, often in response to cold or dry conditions. In temperate regions, many deciduous trees shed leaves in autumn and remain bare through winter. In tropical monsoon climates, deciduous trees may shed leaves during the dry season. Coniferous trees usually have needle like leaves and many species are evergreen, though some conifers can be deciduous. Evergreen trees retain leaves throughout the year and continuously replace them rather than shedding all at once. The simplest and most widely used term for trees that shed their leaves once a year is deciduous.

Step-by-Step Solution:
1. Recognise that the key phrase in the question is shed their leaves once in a year.2. Recall that deciduous trees are defined as those that lose leaves seasonally, becoming leafless for part of the year.3. Common examples include many broadleaf trees such as oak, maple, and Sal in certain climates.4. Coniferous trees like pine and spruce often retain their needles year round and are considered evergreen, even though a few species may shed needles in patterns.5. Evergreen trees by definition do not lose all their leaves at once; they maintain foliage throughout the year.6. Therefore, the correct general term for trees that shed leaves once each year is deciduous trees.

Verification / Alternative check:
Geography textbooks often divide forests into tropical evergreen, tropical deciduous, temperate deciduous, and coniferous types. In these classifications, tropical and temperate deciduous forests are characterised by a marked leaf shedding season. Diagrams show deciduous trees becoming bare in the dry or cold season. Evergreen and coniferous forests are depicted as retaining foliage all year. These descriptions match the idea that deciduous trees shed their leaves once a year.

Why Other Options Are Wrong:
Option B, coniferous trees, is generally incorrect because most conifers are evergreen and do not shed all leaves at once, even though they may gradually lose older needles. Option C, evergreen trees, is the opposite of what the question describes, since evergreen trees maintain foliage year round. Option D, both deciduous and coniferous trees, is misleading because the classic textbook definition associates yearly complete leaf shedding specifically with deciduous trees.

Common Pitfalls:
Students sometimes think that all coniferous trees must be evergreen and all broadleaf trees must be deciduous, which is not strictly true, but for exam purposes the standard pairing is deciduous with seasonal leaf fall and evergreen with year round foliage. Another pitfall is to overthink rare exceptions instead of focusing on common definitions used in school level geography. Remembering that deciduous means falling off at maturity in Latin can help you quickly connect it with leaf fall.

Final Answer:
Trees that shed all their leaves once each year are called deciduous trees.