Shade leaves typically show:
That points to C: Lower respiration rate. Compared with the other options, Lower respiration rate is the one that correctly describes the PSS-Sec-E-Sensory biology concept. The wrong ones are A) Higher Chl a/b ratio; B) Lower chlorophyll content; D) Thicker leaves. If you’re stuck, eliminate anything that contradicts a basic fact you already know for this topic.
Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.