Which of the following statements is true?
a. all animals have a nervous system.
b. all animals sense and respond to the environment.
c. it is necessary to have a nervous system to sense and respond to the environment.
d. all animals have a nervous system, all animals sense and respond to the environment, and it is necessary to have a nervous system to sense and respond to the environment.

The correct answer is B. All animals sense and respond to the environment.

Explanation:

Neurons are the basic unit a nervous system is made up of. It is a complex system which help animals to sense and respond to the change in the internal and external environment.

Most of the multicellular organism have nervous system or nerve cell and sensory cells to sense their environmental change but some animals having very simpler body organization lacks there sensory structures.

Sponges are the multicellular animals that do not have nerve cells but they also respond to the environmental by infiltration-contraction response which is generated by doing significant change in their canal size.

ans.

gregor john mendel is known for study of inheritance in pea plants. he used garden pea plant for his study, having alternative traits for various characters. he performed cross-breeding in pea plants to check how characters are transmitted between parents to offspring, such as cross between pure tall and pure dwarf plant. mendel studied the inheritance patterns in pea plants for various generations.

thus, the correct answer includes options and f).