Primary root is
a) Positively geotropic
b) Positive hydrotropic
c)Negative geotropic
d)Negative hydrotropic

Hint: The root is the part of the plant that helps in the anchoring of the plant. It is the main part of the plant as it provides the plant with nutrition and water from the soil by absorbing it. It is of two types of the taproot and the adventitious root. The roots may also be present in the plant as their modification.

Complete answer: Geotropism is the phenomenon where the plant growth is influenced by the force of gravity exerted by the planet. The force of gravity exerts its force in the downward direction. The part which grows in the direction of the force is regarded as positively geotropic and the plant part which grows opposite to the force of gravity is regarded as the negatively geotropic in nature. As the roots always grow in the downward direction or in the direction of the force of gravity they are regarded as positively geotropic. The shoots of the plant grow against the force of gravity so, it is known to be negatively geotropic in nature. Hydrotropism is the phenomenon where the plant root grows either towards the presence of moisture content in the soil or in the opposite direction. When the root grows towards the presence of the moisture content then the roots are known as positively hydrotropic and when the roots grow away from the moisture content then the root is known to be negatively hydrotropic.


So, the answer is ‘positively geotropic’.

Note: The roots grow towards the soil and have a positive geotropism. Some roots that grow away from the soil are known to be negatively geotropic in nature. The roots find their way by getting attracted to the moisture content in the soil. This helps them to expand their area for absorption of nutrients.