An instrument used for  measuring growth is plants is known as a:

Correct option is D

The correct answer is (D) crescograph.

Explanation: A crescograph is an instrument used to measure the growth of plants. It records the changes in the growth rate of plants over time by measuring the elongation or movement of plant tissues. The instrument helps scientists study the effect of different environmental factors on plant growth.

Information Booster:

• The crescograph was invented by the Indian botanist J.C. Bose in the early 20th century.
• It works by measuring the minute growth movements of plants and amplifying them for detailed analysis.
• The instrument has been used to study various aspects of plant physiology, including the impact of light, temperature, and gravity on growth.

Additional Information:

• A chronometer (A) is an instrument used to measure time with high precision.
• A bolometer (B) is used to measure the power of electromagnetic radiation, particularly in the infrared spectrum.
• A cardiograph (C) is an instrument used to measure and record the heart's activity, not plant growth.