Identify the correct set of statements :

(a) The leaflets are modified into pointed hard thorns in citrus and Bougainvillea.

(b) Axillary buds form slender and spirally coiled tendrils in cucumber and pumpkin

(c) Stem is flattened and fleshy in Opuntia and modified to perform the function of leaves.

(d) Rhizophora shows vertically upward growing roots that help to get oxygen for respiration.

(e) Subaerially growing stems in grasses and strawberries help in vegetative propagation.

Choose the correct answer from the options given below:

Concept: 

• Stems are modified to perform different functions. 
• Some stems perform the function of storage of food, support, protection and vegetative propagation.
• For example, Underground stems of potato, ginger, turmeric, zaminkand, Colocasia are modified to store food in them. 

Explanation:

Statement a:  The leaflets are modified into pointed hard thorns in Citrus and Bougainvillea. This statement is incorrect as axillary buds of stems get modified into woody, straight and pointed thorns. Thorns are found in many plants such as Citrus and Bougainvillea. . They protect plants from browsing animals.  

Statement b: Axillary buds form slender and spirally coiled tendrils in cucumber and pumpkin. This statement is correct.

Statement c: Stem is flattened and fleshy in Opuntia and modified to perform the function of leaves. This statement is correct.

Statement d: Rhizophora shows vertically upward growing roots that help to get oxygen for respiration. This statement is correct.

Statement e: Subaerially growing stems in grasses and strawberries help in vegetative propagation.  This statement is correct.

Only option 4 comprises all correct statements. Therefore, option 4 is the correct answer.