Explanation

In soil science and hydrology, 'ecard' is not a standard term. However, in the context of plant available water, 'effective rainfall' or 'available water' is often discussed. Wait, let's check the specific terminology used in Pakistani agricultural exams (like CSS/FPSC). Often, 'e' stands for evaporation or effective. Actually, looking at common MCQs from this source, 'ecard' might be a typo for 'effective rainfall' or similar? No, wait. Let's look at the options. A: Available water, B: Unavailable water. In soil physics, water is classified as hygroscopic (unavailable), capillary (available), and gravitational (unavailable). Sometimes 'e' refers to evaporation. But let's check if 'ecard' is a known acronym. Actually, in some contexts, 'E' stands for Evapotranspiration. But the options are about water types. Let's reconsider. Is it possible 'ecard' refers to 'Effective Rainfall'? No. Wait, could it be a typo for 'field capacity' or 'wilting point'? No. Let's look at the term 'e' in soil water. 'E' often denotes evaporation. But the options are A: Available, B: Unavailable. In many Pakistani MCQ banks, there is a question: